51511320 has 96 divisors (see below), whose sum is σ = 191337120. Its totient is φ = 11773440.

The previous prime is 51511297. The next prime is 51511321. The reversal of 51511320 is 2311515.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 51511293 and 51511302.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51511321) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 7701 + ... + 12740.

It is an arithmetic number, because the mean of its divisors is an integer number (1993095).

Almost surely, 2^51511320 is an apocalyptic number.

It is an amenable number.

51511320 is an abundant number, since it is smaller than the sum of its proper divisors (139825800).

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

51511320 is a wasteful number, since it uses less digits than its factorization.

51511320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20465 (or 20458 counting only the distinct ones).

The product of its (nonzero) digits is 150, while the sum is 18.

The square root of 51511320 is about 7177.1387056403. The cubic root of 51511320 is about 372.0782006947.

Adding to 51511320 its reverse (2311515), we get a palindrome (53822835).

The spelling of 51511320 in words is "fifty-one million, five hundred eleven thousand, three hundred twenty".