51821971825 has 24 divisors (see below), whose sum is σ = 70150272248. Its totient is φ = 37744289280.

The previous prime is 51821971793. The next prime is 51821971829. The reversal of 51821971825 is 52817912815.

It is a happy number.

It can be written as a sum of positive squares in 12 ways, for example, as 33474727521 + 18347244304 = 182961^2 + 135452^2 .

It is not a de Polignac number, because 51821971825 - 2⁵ = 51821971793 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (51821971829) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1068414 + ... + 1115863.

Almost surely, 2^51821971825 is an apocalyptic number.

It is an amenable number.

51821971825 is a deficient number, since it is larger than the sum of its proper divisors (18328300423).

51821971825 is a wasteful number, since it uses less digits than its factorization.

51821971825 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2184373 (or 2184368 counting only the distinct ones).

The product of its digits is 403200, while the sum is 49.

The spelling of 51821971825 in words is "fifty-one billion, eight hundred twenty-one million, nine hundred seventy-one thousand, eight hundred twenty-five".