2551040021 has 4 divisors (see below), whose sum is σ = 2552524044. Its totient is φ = 2549556000.

The previous prime is 2551039979. The next prime is 2551040027. The reversal of 2551040021 is 1200401552.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 2142393796 + 408646225 = 46286^2 + 20215^2 .

It is a cyclic number.

It is not a de Polignac number, because 2551040021 - 2¹⁸ = 2550777877 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 2551039975 and 2551040002.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2551040027) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 739430 + ... + 742871.

It is an arithmetic number, because the mean of its divisors is an integer number (638131011).

Almost surely, 2^2551040021 is an apocalyptic number.

It is an amenable number.

2551040021 is a deficient number, since it is larger than the sum of its proper divisors (1484023).

2551040021 is a wasteful number, since it uses less digits than its factorization.

2551040021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1484022.

The product of its (nonzero) digits is 400, while the sum is 20.

The square root of 2551040021 is about 50507.8213844153. The cubic root of 2551040021 is about 1366.3829179377.

Adding to 2551040021 its reverse (1200401552), we get a palindrome (3751441573).

The spelling of 2551040021 in words is "two billion, five hundred fifty-one million, forty thousand, twenty-one".