66861920 has 48 divisors (see below), whose sum is σ = 164838240. Its totient is φ = 25580544.

The previous prime is 66861911. The next prime is 66861929. The reversal of 66861920 is 2916866.

It is an interprime number because it is at equal distance from previous prime (66861911) and next prime (66861929).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66861929) 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, 5405 + ... + 12764.

It is an arithmetic number, because the mean of its divisors is an integer number (3434130).

Almost surely, 2^66861920 is an apocalyptic number.

It is an amenable number.

66861920 is an abundant number, since it is smaller than the sum of its proper divisors (97976320).

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

66861920 is a wasteful number, since it uses less digits than its factorization.

66861920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18207 (or 18199 counting only the distinct ones).

The product of its (nonzero) digits is 31104, while the sum is 38.

The square root of 66861920 is about 8176.9138432541. The cubic root of 66861920 is about 405.8756039420.

The spelling of 66861920 in words is "sixty-six million, eight hundred sixty-one thousand, nine hundred twenty".