161523621 has 12 divisors (see below), whose sum is σ = 266642272. Its totient is φ = 92299176.

The previous prime is 161523601. The next prime is 161523623. The reversal of 161523621 is 126325161.

161523621 is a `hidden beast` number, since 1 + 6 + 15 + 23 + 621 = 666.

It is not a de Polignac number, because 161523621 - 2⁷ = 161523493 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 (161523623) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1281871 + ... + 1281996.

Almost surely, 2^161523621 is an apocalyptic number.

It is an amenable number.

161523621 is a deficient number, since it is larger than the sum of its proper divisors (105118651).

161523621 is a wasteful number, since it uses less digits than its factorization.

161523621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2563880 (or 2563877 counting only the distinct ones).

The product of its digits is 2160, while the sum is 27.

The square root of 161523621 is about 12709.1943489743. The cubic root of 161523621 is about 544.6013087253.

Adding to 161523621 its reverse (126325161), we get a palindrome (287848782).

The spelling of 161523621 in words is "one hundred sixty-one million, five hundred twenty-three thousand, six hundred twenty-one".