66415566 has 64 divisors (see below), whose sum is σ = 161989632. Its totient is φ = 17720832.

The previous prime is 66415541. The next prime is 66415567. The reversal of 66415566 is 66551466.

It is a super-2 number, since 2×66415566² = 8822054814200712, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66415567) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 118960 + ... + 119516.

It is an arithmetic number, because the mean of its divisors is an integer number (2531088).

Almost surely, 2^66415566 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 66415566, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (80994816).

66415566 is an abundant number, since it is smaller than the sum of its proper divisors (95574066).

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

66415566 is a wasteful number, since it uses less digits than its factorization.

66415566 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 753.

The product of its digits is 129600, while the sum is 39.

The square root of 66415566 is about 8149.5745901243. The cubic root of 66415566 is about 404.9704108851.

The spelling of 66415566 in words is "sixty-six million, four hundred fifteen thousand, five hundred sixty-six".