51778815 has 32 divisors (see below), whose sum is σ = 91238400. Its totient is φ = 24865920.

The previous prime is 51778807. The next prime is 51778817. The reversal of 51778815 is 51887715.

It is not a de Polignac number, because 51778815 - 2³ = 51778807 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51778817) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 16546 + ... + 19424.

It is an arithmetic number, because the mean of its divisors is an integer number (2851200).

Almost surely, 2^51778815 is an apocalyptic number.

51778815 is a gapful number since it is divisible by the number (55) formed by its first and last digit.

51778815 is a deficient number, since it is larger than the sum of its proper divisors (39459585).

51778815 is a wasteful number, since it uses less digits than its factorization.

51778815 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3007.

The product of its digits is 78400, while the sum is 42.

The square root of 51778815 is about 7195.7497872008. The cubic root of 51778815 is about 372.7211485032.

Subtracting 51778815 from its reverse (51887715), we obtain a square (108900 = 330²).

The spelling of 51778815 in words is "fifty-one million, seven hundred seventy-eight thousand, eight hundred fifteen".