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161899861 is a prime number
BaseRepresentation
bin10011010011001…
…10010101010101
3102021122100212011
421221212111111
5312421243421
624022024221
74004061154
oct1151462525
9367570764
10161899861
118342a842
1246278071
1327707446
141770559b
15e3304e1
hex9a66555

161899861 has 2 divisors, whose sum is σ = 161899862. Its totient is φ = 161899860.

The previous prime is 161899849. The next prime is 161899867. The reversal of 161899861 is 168998161.

It is a happy number.

161899861 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 136749636 + 25150225 = 11694^2 + 5015^2 .

It is an emirp because it is prime and its reverse (168998161) is a distict prime. It is also a bemirp because it and its reverse can be mirrored producing other two distinct primes, 198668191 and 191866891.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2k-161899861 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (161899867) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80949930 + 80949931.

It is an arithmetic number, because the mean of its divisors is an integer number (80949931).

Almost surely, 2161899861 is an apocalyptic number.

It is an amenable number.

161899861 is a deficient number, since it is larger than the sum of its proper divisors (1).

161899861 is an equidigital number, since it uses as much as digits as its factorization.

161899861 is an evil number, because the sum of its binary digits is even.

The product of its digits is 186624, while the sum is 49.

The square root of 161899861 is about 12723.9876218110. The cubic root of 161899861 is about 545.0238308464.

The spelling of 161899861 in words is "one hundred sixty-one million, eight hundred ninety-nine thousand, eight hundred sixty-one".