51563531621 has 4 divisors (see below), whose sum is σ = 58929750432. Its totient is φ = 44197312812.

The previous prime is 51563531587. The next prime is 51563531629. The reversal of 51563531621 is 12613536515.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 51563531621 - 2¹⁸ = 51563269477 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51563531629) 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, 3683109395 + ... + 3683109408.

It is an arithmetic number, because the mean of its divisors is an integer number (14732437608).

Almost surely, 2^51563531621 is an apocalyptic number.

It is an amenable number.

51563531621 is a deficient number, since it is larger than the sum of its proper divisors (7366218811).

51563531621 is an equidigital number, since it uses as much as digits as its factorization.

51563531621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7366218810.

The product of its digits is 81000, while the sum is 38.

The spelling of 51563531621 in words is "fifty-one billion, five hundred sixty-three million, five hundred thirty-one thousand, six hundred twenty-one".