161550021 has 16 divisors (see below), whose sum is σ = 226001408. Its totient is φ = 102513600.

The previous prime is 161550013. The next prime is 161550073. The reversal of 161550021 is 120055161.

It is not a de Polignac number, because 161550021 - 2³ = 161550013 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 161550021.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161550721) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8566 + ... + 19911.

It is an arithmetic number, because the mean of its divisors is an integer number (14125088).

Almost surely, 2^161550021 is an apocalyptic number.

It is an amenable number.

161550021 is a deficient number, since it is larger than the sum of its proper divisors (64451387).

161550021 is a wasteful number, since it uses less digits than its factorization.

161550021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28572.

The product of its (nonzero) digits is 300, while the sum is 21.

The square root of 161550021 is about 12710.2329246950. The cubic root of 161550021 is about 544.6309776394.

The spelling of 161550021 in words is "one hundred sixty-one million, five hundred fifty thousand, twenty-one".