78157215 has 12 divisors (see below), whose sum is σ = 135472584. Its totient is φ = 41683824.

The previous prime is 78157207. The next prime is 78157217. The reversal of 78157215 is 51275187.

78157215 is a `hidden beast` number, since 7 + 81 + 572 + 1 + 5 = 666.

It is not a de Polignac number, because 78157215 - 2³ = 78157207 is a prime.

It is a super-2 number, since 2×78157215² = 12217100513112450, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 78157215.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78157217) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 868369 + ... + 868458.

It is an arithmetic number, because the mean of its divisors is an integer number (11289382).

Almost surely, 2^78157215 is an apocalyptic number.

78157215 is a deficient number, since it is larger than the sum of its proper divisors (57315369).

78157215 is a wasteful number, since it uses less digits than its factorization.

78157215 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1736838 (or 1736835 counting only the distinct ones).

The product of its digits is 19600, while the sum is 36.

The square root of 78157215 is about 8840.6569326040. The cubic root of 78157215 is about 427.5527379280.

The spelling of 78157215 in words is "seventy-eight million, one hundred fifty-seven thousand, two hundred fifteen".