51615390 has 16 divisors (see below), whose sum is σ = 123877008. Its totient is φ = 13764096.

The previous prime is 51615373. The next prime is 51615397. The reversal of 51615390 is 9351615.

It is a Harshad number since it is a multiple of its sum of digits (30), and also a Moran number because the ratio is a prime number: 1720513 = 51615390 / (5 + 1 + 6 + 1 + 5 + 3 + 9 + 0).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51615397) 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, 860227 + ... + 860286.

It is an arithmetic number, because the mean of its divisors is an integer number (7742313).

Almost surely, 2^51615390 is an apocalyptic number.

51615390 is an abundant number, since it is smaller than the sum of its proper divisors (72261618).

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

51615390 is a wasteful number, since it uses less digits than its factorization.

51615390 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1720523.

The product of its (nonzero) digits is 4050, while the sum is 30.

The square root of 51615390 is about 7184.3851511455. The cubic root of 51615390 is about 372.3286060447.

The spelling of 51615390 in words is "fifty-one million, six hundred fifteen thousand, three hundred ninety".