72738021 has 4 divisors (see below), whose sum is σ = 96984032. Its totient is φ = 48492012.

The previous prime is 72738011. The next prime is 72738031. The reversal of 72738021 is 12083727.

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, and also an emirpimes, since its reverse is a distinct semiprime: 12083727 = 3 ⋅4027909.

It is an interprime number because it is at equal distance from previous prime (72738011) and next prime (72738031).

It is not a de Polignac number, because 72738021 - 2²⁶ = 5629157 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 72738021.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (72738011) 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, 12123001 + ... + 12123006.

It is an arithmetic number, because the mean of its divisors is an integer number (24246008).

Almost surely, 2^72738021 is an apocalyptic number.

It is an amenable number.

72738021 is a deficient number, since it is larger than the sum of its proper divisors (24246011).

72738021 is a wasteful number, since it uses less digits than its factorization.

72738021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24246010.

The product of its (nonzero) digits is 4704, while the sum is 30.

The square root of 72738021 is about 8528.6588042904. The cubic root of 72738021 is about 417.4333664439.

The spelling of 72738021 in words is "seventy-two million, seven hundred thirty-eight thousand, twenty-one".