72163921 has 2 divisors, whose sum is σ = 72163922. Its totient is φ = 72163920.

The previous prime is 72163913. The next prime is 72163961. The reversal of 72163921 is 12936127.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 53363025 + 18800896 = 7305^2 + 4336^2 .

It is a cyclic number.

It is not a de Polignac number, because 72163921 - 2³ = 72163913 is a prime.

It is not a weakly prime, because it can be changed into another prime (72163961) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 36081960 + 36081961.

It is an arithmetic number, because the mean of its divisors is an integer number (36081961).

Almost surely, 2^72163921 is an apocalyptic number.

It is an amenable number.

72163921 is a deficient number, since it is larger than the sum of its proper divisors (1).

72163921 is an equidigital number, since it uses as much as digits as its factorization.

72163921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4536, while the sum is 31.

The square root of 72163921 is about 8494.9350203518. The cubic root of 72163921 is about 416.3322377471.

The spelling of 72163921 in words is "seventy-two million, one hundred sixty-three thousand, nine hundred twenty-one".