51639984 has 80 divisors (see below), whose sum is σ = 161715840. Its totient is φ = 15647040.

The previous prime is 51639979. The next prime is 51639989. The reversal of 51639984 is 48993615.

It is a happy number.

51639984 is a `hidden beast` number, since 5 + 1 + 639 + 9 + 8 + 4 = 666.

It is an interprime number because it is at equal distance from previous prime (51639979) and next prime (51639989).

It is not an unprimeable number, because it can be changed into a prime (51639989) 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, 682 + ... + 10185.

It is an arithmetic number, because the mean of its divisors is an integer number (2021448).

Almost surely, 2^51639984 is an apocalyptic number.

51639984 is a gapful number since it is divisible by the number (54) 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 51639984, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (80857920).

51639984 is an abundant number, since it is smaller than the sum of its proper divisors (110075856).

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

51639984 is a wasteful number, since it uses less digits than its factorization.

51639984 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10895 (or 10883 counting only the distinct ones).

The product of its digits is 233280, while the sum is 45.

The square root of 51639984 is about 7186.0965760279. The cubic root of 51639984 is about 372.3877330849.

The spelling of 51639984 in words is "fifty-one million, six hundred thirty-nine thousand, nine hundred eighty-four".