66129720 has 64 divisors (see below), whose sum is σ = 203243040. Its totient is φ = 17203200.

The previous prime is 66129719. The next prime is 66129731. The reversal of 66129720 is 2792166.

It is a congruent number.

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, 1801 + ... + 11640.

Almost surely, 2^66129720 is an apocalyptic number.

66129720 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 66129720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (101621520).

66129720 is an abundant number, since it is smaller than the sum of its proper divisors (137113320).

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

66129720 is a wasteful number, since it uses less digits than its factorization.

66129720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13496 (or 13492 counting only the distinct ones).

The product of its (nonzero) digits is 9072, while the sum is 33.

The square root of 66129720 is about 8132.0181996845. The cubic root of 66129720 is about 404.3885912441.

It can be divided in two parts, 661 and 29720, that added together give a triangular number (30381 = T₂₄₆).

The spelling of 66129720 in words is "sixty-six million, one hundred twenty-nine thousand, seven hundred twenty".