72581021 has 2 divisors, whose sum is σ = 72581022. Its totient is φ = 72581020.

The previous prime is 72581011. The next prime is 72581023. The reversal of 72581021 is 12018527.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 64802500 + 7778521 = 8050^2 + 2789^2 .

It is a cyclic number.

It is not a de Polignac number, because 72581021 - 2²⁶ = 5472157 is a prime.

Together with 72581023, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (72581023) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 36290510 + 36290511.

It is an arithmetic number, because the mean of its divisors is an integer number (36290511).

Almost surely, 2^72581021 is an apocalyptic number.

It is an amenable number.

72581021 is a deficient number, since it is larger than the sum of its proper divisors (1).

72581021 is an equidigital number, since it uses as much as digits as its factorization.

72581021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1120, while the sum is 26.

The square root of 72581021 is about 8519.4495714219. The cubic root of 72581021 is about 417.1328163939.

Adding to 72581021 its reverse (12018527), we get a palindrome (84599548).

The spelling of 72581021 in words is "seventy-two million, five hundred eighty-one thousand, twenty-one".