51405984 has 144 divisors (see below), whose sum is σ = 171243072. Its totient is φ = 14321664.

The previous prime is 51405973. The next prime is 51405997. The reversal of 51405984 is 48950415.

It is a tau number, because it is divible by the number of its divisors (144).

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 86392 + ... + 86984.

It is an arithmetic number, because the mean of its divisors is an integer number (1189188).

Almost surely, 2^51405984 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 51405984, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (85621536).

51405984 is an abundant number, since it is smaller than the sum of its proper divisors (119837088).

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

51405984 is a wasteful number, since it uses less digits than its factorization.

51405984 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 659 (or 648 counting only the distinct ones).

The product of its (nonzero) digits is 28800, while the sum is 36.

The square root of 51405984 is about 7169.7966498360. The cubic root of 51405984 is about 371.8244055076.

The spelling of 51405984 in words is "fifty-one million, four hundred five thousand, nine hundred eighty-four".