66666915 has 128 divisors (see below), whose sum is σ = 147456000. Its totient is φ = 27900288.

The previous prime is 66666913. The next prime is 66666923. The reversal of 66666915 is 51966666.

It is not a de Polignac number, because 66666915 - 2¹ = 66666913 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

Its product of digits (349920) is a multiple of the sum of its prime divisors (160).

It is not an unprimeable number, because it can be changed into a prime (66666913) by changing a digit.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 843846 + ... + 843924.

It is an arithmetic number, because the mean of its divisors is an integer number (1152000).

Almost surely, 2^66666915 is an apocalyptic number.

66666915 is an abundant number, since it is smaller than the sum of its proper divisors (80789085).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

66666915 is a wasteful number, since it uses less digits than its factorization.

66666915 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 166 (or 160 counting only the distinct ones).

The product of its digits is 349920, while the sum is 45.

The square root of 66666915 is about 8164.9810165119. The cubic root of 66666915 is about 405.4806365088.

The spelling of 66666915 in words is "sixty-six million, six hundred sixty-six thousand, nine hundred fifteen".