66515620 has 24 divisors (see below), whose sum is σ = 141975288. Its totient is φ = 26169600.

The previous prime is 66515567. The next prime is 66515623. The reversal of 66515620 is 2651566.

It can be written as a sum of positive squares in 4 ways, for example, as 60516 + 66455104 = 246^2 + 8152^2 .

It is a hoax number, since the sum of its digits (31) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (66515623) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 26041 + ... + 28480.

It is an arithmetic number, because the mean of its divisors is an integer number (5915637).

Almost surely, 2^66515620 is an apocalyptic number.

It is an amenable number.

66515620 is an abundant number, since it is smaller than the sum of its proper divisors (75459668).

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

66515620 is a wasteful number, since it uses less digits than its factorization.

66515620 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 54591 (or 54589 counting only the distinct ones).

The product of its (nonzero) digits is 10800, while the sum is 31.

The square root of 66515620 is about 8155.7108825657. The cubic root of 66515620 is about 405.1736693575.

The spelling of 66515620 in words is "sixty-six million, five hundred fifteen thousand, six hundred twenty".