161901681437 has 2 divisors, whose sum is σ = 161901681438. Its totient is φ = 161901681436.

The previous prime is 161901681433. The next prime is 161901681439. The reversal of 161901681437 is 734186109161.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 147537419236 + 14364262201 = 384106^2 + 119851^2 .

It is a cyclic number.

It is not a de Polignac number, because 161901681437 - 2² = 161901681433 is a prime.

It is a super-3 number, since 3×161901681437³ (a number of 35 digits) contains 333 as substring.

Together with 161901681439, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 161901681391 and 161901681400.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (161901681433) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80950840718 + 80950840719.

It is an arithmetic number, because the mean of its divisors is an integer number (80950840719).

Almost surely, 2^161901681437 is an apocalyptic number.

It is an amenable number.

161901681437 is a deficient number, since it is larger than the sum of its proper divisors (1).

161901681437 is an equidigital number, since it uses as much as digits as its factorization.

161901681437 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 217728, while the sum is 47.

The spelling of 161901681437 in words is "one hundred sixty-one billion, nine hundred one million, six hundred eighty-one thousand, four hundred thirty-seven".