72311021 has 2 divisors, whose sum is σ = 72311022. Its totient is φ = 72311020.

The previous prime is 72310999. The next prime is 72311039. The reversal of 72311021 is 12011327.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 71588521 + 722500 = 8461^2 + 850^2 .

It is a cyclic number.

It is not a de Polignac number, because 72311021 - 2¹⁰ = 72309997 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (72311621) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 36155510 + 36155511.

It is an arithmetic number, because the mean of its divisors is an integer number (36155511).

Almost surely, 2^72311021 is an apocalyptic number.

It is an amenable number.

72311021 is a deficient number, since it is larger than the sum of its proper divisors (1).

72311021 is an equidigital number, since it uses as much as digits as its factorization.

72311021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 84, while the sum is 17.

The square root of 72311021 is about 8503.5887130082. The cubic root of 72311021 is about 416.6149316744.

Adding to 72311021 its reverse (12011327), we get a palindrome (84322348).

The spelling of 72311021 in words is "seventy-two million, three hundred eleven thousand, twenty-one".