72561921 has 8 divisors (see below), whose sum is σ = 99364224. Its totient is φ = 47067120.

The previous prime is 72561911. The next prime is 72561977. The reversal of 72561921 is 12916527.

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

It is not a de Polignac number, because 72561921 - 2¹³ = 72553729 is a prime.

It is not an unprimeable number, because it can be changed into a prime (72561901) 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, 326745 + ... + 326966.

It is an arithmetic number, because the mean of its divisors is an integer number (12420528).

Almost surely, 2^72561921 is an apocalyptic number.

It is an amenable number.

72561921 is a deficient number, since it is larger than the sum of its proper divisors (26802303).

72561921 is a wasteful number, since it uses less digits than its factorization.

72561921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 653751.

The product of its digits is 7560, while the sum is 33.

The square root of 72561921 is about 8518.3285332276. The cubic root of 72561921 is about 417.0962231006.

The spelling of 72561921 in words is "seventy-two million, five hundred sixty-one thousand, nine hundred twenty-one".