72307891 has 4 divisors (see below), whose sum is σ = 73326384. Its totient is φ = 71289400.

The previous prime is 72307889. The next prime is 72307931. The reversal of 72307891 is 19870327.

72307891 = 3469² + 3470² + ... + 3474².

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 19870327 = 2087 ⋅9521.

It is a cyclic number.

It is not a de Polignac number, because 72307891 - 2¹ = 72307889 is a prime.

It is a super-2 number, since 2×72307891² = 10456862201735762, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 72307891.

It is not an unprimeable number, because it can be changed into a prime (72301891) 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, 509140 + ... + 509281.

It is an arithmetic number, because the mean of its divisors is an integer number (18331596).

Almost surely, 2^72307891 is an apocalyptic number.

72307891 is a gapful number since it is divisible by the number (71) formed by its first and last digit.

72307891 is a deficient number, since it is larger than the sum of its proper divisors (1018493).

72307891 is a wasteful number, since it uses less digits than its factorization.

72307891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1018492.

The product of its (nonzero) digits is 21168, while the sum is 37.

The square root of 72307891 is about 8503.4046710715. The cubic root of 72307891 is about 416.6089204951.

The spelling of 72307891 in words is "seventy-two million, three hundred seven thousand, eight hundred ninety-one".