72165021 has 32 divisors (see below), whose sum is σ = 105840000. Its totient is φ = 43561728.

The previous prime is 72165001. The next prime is 72165029. The reversal of 72165021 is 12056127.

It is not a de Polignac number, because 72165021 - 2⁹ = 72164509 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 72164982 and 72165000.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (72165029) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 246151 + ... + 246443.

It is an arithmetic number, because the mean of its divisors is an integer number (3307500).

Almost surely, 2^72165021 is an apocalyptic number.

It is an amenable number.

72165021 is a deficient number, since it is larger than the sum of its proper divisors (33674979).

72165021 is a wasteful number, since it uses less digits than its factorization.

72165021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 493.

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

The square root of 72165021 is about 8494.9997645674. Note that the first 3 decimals coincide. The cubic root of 72165021 is about 416.3343531308.

The spelling of 72165021 in words is "seventy-two million, one hundred sixty-five thousand, twenty-one".