51718821 has 32 divisors (see below), whose sum is σ = 87180288. Its totient is φ = 26490240.

The previous prime is 51718813. The next prime is 51718837. The reversal of 51718821 is 12881715.

It is not a de Polignac number, because 51718821 - 2³ = 51718813 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51718871) 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, 15330 + ... + 18396.

It is an arithmetic number, because the mean of its divisors is an integer number (2724384).

Almost surely, 2^51718821 is an apocalyptic number.

It is an amenable number.

51718821 is a deficient number, since it is larger than the sum of its proper divisors (35461467).

51718821 is a wasteful number, since it uses less digits than its factorization.

51718821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3161.

The product of its digits is 4480, while the sum is 33.

The square root of 51718821 is about 7191.5798681514. The cubic root of 51718821 is about 372.5771406085.

The spelling of 51718821 in words is "fifty-one million, seven hundred eighteen thousand, eight hundred twenty-one".