72911921 has 2 divisors, whose sum is σ = 72911922. Its totient is φ = 72911920.

The previous prime is 72911821. The next prime is 72911933. The reversal of 72911921 is 12911927.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 62094400 + 10817521 = 7880^2 + 3289^2 .

It is a cyclic number.

It is not a de Polignac number, because 72911921 - 2¹⁸ = 72649777 is a prime.

It is a super-2 number, since 2×72911921² = 10632296447820482, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (72911221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 36455960 + 36455961.

It is an arithmetic number, because the mean of its divisors is an integer number (36455961).

Almost surely, 2^72911921 is an apocalyptic number.

It is an amenable number.

72911921 is a deficient number, since it is larger than the sum of its proper divisors (1).

72911921 is an equidigital number, since it uses as much as digits as its factorization.

72911921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2268, while the sum is 32.

The square root of 72911921 is about 8538.8477559914. The cubic root of 72911921 is about 417.7657643110.

The spelling of 72911921 in words is "seventy-two million, nine hundred eleven thousand, nine hundred twenty-one".