51821765 has 16 divisors (see below), whose sum is σ = 63927360. Its totient is φ = 40312320.

The previous prime is 51821747. The next prime is 51821767. The reversal of 51821765 is 56712815.

It is not a de Polignac number, because 51821765 - 2²⁴ = 35044549 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51821767) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 27710 + ... + 29520.

It is an arithmetic number, because the mean of its divisors is an integer number (3995460).

Almost surely, 2^51821765 is an apocalyptic number.

It is an amenable number.

51821765 is a deficient number, since it is larger than the sum of its proper divisors (12105595).

51821765 is a wasteful number, since it uses less digits than its factorization.

51821765 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1972.

The product of its digits is 16800, while the sum is 35.

The square root of 51821765 is about 7198.7335691773. The cubic root of 51821765 is about 372.8241761546.

The spelling of 51821765 in words is "fifty-one million, eight hundred twenty-one thousand, seven hundred sixty-five".