66415920 has 80 divisors (see below), whose sum is σ = 207605760. Its totient is φ = 17563392.

The previous prime is 66415913. The next prime is 66415931. The reversal of 66415920 is 2951466.

It is a tau number, because it is divible by the number of its divisors (80).

It is a super-2 number, since 2×66415920² = 8822148858892800, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 29391 + ... + 31569.

It is an arithmetic number, because the mean of its divisors is an integer number (2595072).

Almost surely, 2^66415920 is an apocalyptic number.

66415920 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 66415920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (103802880).

66415920 is an abundant number, since it is smaller than the sum of its proper divisors (141189840).

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

66415920 is a wasteful number, since it uses less digits than its factorization.

66415920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2322 (or 2316 counting only the distinct ones).

The product of its (nonzero) digits is 12960, while the sum is 33.

The square root of 66415920 is about 8149.5963090205. The cubic root of 66415920 is about 404.9711303915.

It can be divided in two parts, 6641 and 5920, that added together give a triangular number (12561 = T₁₅₈).

The spelling of 66415920 in words is "sixty-six million, four hundred fifteen thousand, nine hundred twenty".