161865901 has 4 divisors (see below), whose sum is σ = 162897052. Its totient is φ = 160834752.

The previous prime is 161865887. The next prime is 161865923. The reversal of 161865901 is 109568161.

161865901 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 93141801 + 68724100 = 9651^2 + 8290^2 .

It is a cyclic number.

It is not a de Polignac number, because 161865901 - 2⁷ = 161865773 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161865931) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 515340 + ... + 515653.

It is an arithmetic number, because the mean of its divisors is an integer number (40724263).

Almost surely, 2^161865901 is an apocalyptic number.

It is an amenable number.

161865901 is a deficient number, since it is larger than the sum of its proper divisors (1031151).

161865901 is a wasteful number, since it uses less digits than its factorization.

161865901 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1031150.

The product of its (nonzero) digits is 12960, while the sum is 37.

The square root of 161865901 is about 12722.6530645145. The cubic root of 161865901 is about 544.9857202442.

The spelling of 161865901 in words is "one hundred sixty-one million, eight hundred sixty-five thousand, nine hundred one".