51397920 has 144 divisors (see below), whose sum is σ = 200491200. Its totient is φ = 11745792.

The previous prime is 51397903. The next prime is 51397933. The reversal of 51397920 is 2979315.

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

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

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 7531 + ... + 12629.

It is an arithmetic number, because the mean of its divisors is an integer number (1392300).

Almost surely, 2^51397920 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 51397920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (100245600).

51397920 is an abundant number, since it is smaller than the sum of its proper divisors (149093280).

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

51397920 is a wasteful number, since it uses less digits than its factorization.

51397920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5127 (or 5116 counting only the distinct ones).

The product of its (nonzero) digits is 17010, while the sum is 36.

The square root of 51397920 is about 7169.2342687347. The cubic root of 51397920 is about 371.8049619295.

The spelling of 51397920 in words is "fifty-one million, three hundred ninety-seven thousand, nine hundred twenty".