66656920 has 64 divisors (see below), whose sum is σ = 164656800. Its totient is φ = 24084480.

The previous prime is 66656911. The next prime is 66656927. The reversal of 66656920 is 2965666.

It is a Harshad number since it is a multiple of its sum of digits (40).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66656927) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 86296 + ... + 87064.

Almost surely, 2^66656920 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 66656920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (82328400).

66656920 is an abundant number, since it is smaller than the sum of its proper divisors (97999880).

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

66656920 is a wasteful number, since it uses less digits than its factorization.

66656920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 988 (or 984 counting only the distinct ones).

The product of its (nonzero) digits is 116640, while the sum is 40.

The square root of 66656920 is about 8164.3689284598. The cubic root of 66656920 is about 405.4603716767.

It can be divided in two parts, 66656 and 920, that added together give a palindrome (67576).

The spelling of 66656920 in words is "sixty-six million, six hundred fifty-six thousand, nine hundred twenty".