72215657 has 4 divisors (see below), whose sum is σ = 72471120. Its totient is φ = 71960196.

The previous prime is 72215617. The next prime is 72215659. The reversal of 72215657 is 75651227.

It is a happy number.

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, and also an emirpimes, since its reverse is a distinct semiprime: 75651227 = 29 ⋅2608663.

It is a cyclic number.

It is not a de Polignac number, because 72215657 - 2⁶ = 72215593 is a prime.

It is a super-2 number, since 2×72215657² = 10430202231883298, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (72215659) 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, 127307 + ... + 127872.

It is an arithmetic number, because the mean of its divisors is an integer number (18117780).

Almost surely, 2^72215657 is an apocalyptic number.

It is an amenable number.

72215657 is a deficient number, since it is larger than the sum of its proper divisors (255463).

72215657 is a wasteful number, since it uses less digits than its factorization.

72215657 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 255462.

The product of its digits is 29400, while the sum is 35.

The square root of 72215657 is about 8497.9795834069. The cubic root of 72215657 is about 416.4317067479.

The spelling of 72215657 in words is "seventy-two million, two hundred fifteen thousand, six hundred fifty-seven".