72517821 has 4 divisors (see below), whose sum is σ = 96690432. Its totient is φ = 48345212.

The previous prime is 72517787. The next prime is 72517843. The reversal of 72517821 is 12871527.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 72517821 - 2²⁵ = 38963389 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (72517021) 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, 12086301 + ... + 12086306.

It is an arithmetic number, because the mean of its divisors is an integer number (24172608).

Almost surely, 2^72517821 is an apocalyptic number.

It is an amenable number.

72517821 is a deficient number, since it is larger than the sum of its proper divisors (24172611).

72517821 is a wasteful number, since it uses less digits than its factorization.

72517821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24172610.

The product of its digits is 7840, while the sum is 33.

The square root of 72517821 is about 8515.7396038160. The cubic root of 72517821 is about 417.0117082900.

The spelling of 72517821 in words is "seventy-two million, five hundred seventeen thousand, eight hundred twenty-one".