72156021 has 16 divisors (see below), whose sum is σ = 112510464. Its totient is φ = 40272624.

The previous prime is 72156017. The next prime is 72156059. The reversal of 72156021 is 12065127.

It is not a de Polignac number, because 72156021 - 2² = 72156017 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 72155982 and 72156000.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (72156011) 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, 39051 + ... + 40856.

It is an arithmetic number, because the mean of its divisors is an integer number (7031904).

Almost surely, 2^72156021 is an apocalyptic number.

It is an amenable number.

72156021 is a deficient number, since it is larger than the sum of its proper divisors (40354443).

72156021 is a wasteful number, since it uses less digits than its factorization.

72156021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 79960.

The product of its (nonzero) digits is 840, while the sum is 24.

The square root of 72156021 is about 8494.4700246690. The cubic root of 72156021 is about 416.3170448148.

The spelling of 72156021 in words is "seventy-two million, one hundred fifty-six thousand, twenty-one".