72315781 has 4 divisors (see below), whose sum is σ = 72364192. Its totient is φ = 72267372.

The previous prime is 72315779. The next prime is 72315787. The reversal of 72315781 is 18751327.

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.

It is a cyclic number.

It is not a de Polignac number, because 72315781 - 2¹ = 72315779 is a prime.

It is a super-2 number, since 2×72315781² = 10459144363279922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (72315787) 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, 21891 + ... + 24976.

It is an arithmetic number, because the mean of its divisors is an integer number (18091048).

Almost surely, 2^72315781 is an apocalyptic number.

It is an amenable number.

72315781 is a deficient number, since it is larger than the sum of its proper divisors (48411).

72315781 is a wasteful number, since it uses less digits than its factorization.

72315781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 48410.

The product of its digits is 11760, while the sum is 34.

The square root of 72315781 is about 8503.8685902359. The cubic root of 72315781 is about 416.6240729438.

The spelling of 72315781 in words is "seventy-two million, three hundred fifteen thousand, seven hundred eighty-one".