161864521 has 8 divisors (see below), whose sum is σ = 199217984. Its totient is φ = 128068560.

The previous prime is 161864471. The next prime is 161864551. The reversal of 161864521 is 125468161.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 161864521 - 2¹¹ = 161862473 is a prime.

It is a super-5 number, since 5×161864521⁵ (a number of 42 digits) contains 55555 as substring.

It is not an unprimeable number, because it can be changed into a prime (161864551) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 889275 + ... + 889456.

It is an arithmetic number, because the mean of its divisors is an integer number (24902248).

Almost surely, 2^161864521 is an apocalyptic number.

It is an amenable number.

161864521 is a deficient number, since it is larger than the sum of its proper divisors (37353463).

161864521 is a wasteful number, since it uses less digits than its factorization.

161864521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1778751.

The product of its digits is 11520, while the sum is 34.

The square root of 161864521 is about 12722.5988304277. The cubic root of 161864521 is about 544.9841714675.

The spelling of 161864521 in words is "one hundred sixty-one million, eight hundred sixty-four thousand, five hundred twenty-one".