51989821 has 32 divisors (see below), whose sum is σ = 61931520. Its totient is φ = 43243200.

The previous prime is 51989809. The next prime is 51989843. The reversal of 51989821 is 12898915.

It is not a de Polignac number, because 51989821 - 2¹¹ = 51987773 is a prime.

It is a super-2 number, since 2×51989821² = 5405882975224082, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51989801) 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, 658060 + ... + 658138.

It is an arithmetic number, because the mean of its divisors is an integer number (1935360).

Almost surely, 2^51989821 is an apocalyptic number.

It is an amenable number.

51989821 is a deficient number, since it is larger than the sum of its proper divisors (9941699).

51989821 is a wasteful number, since it uses less digits than its factorization.

51989821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 217.

The product of its digits is 51840, while the sum is 43.

The square root of 51989821 is about 7210.3967297230. The cubic root of 51989821 is about 373.2267594571.

The spelling of 51989821 in words is "fifty-one million, nine hundred eighty-nine thousand, eight hundred twenty-one".