51981563 has 18 divisors (see below), whose sum is σ = 57127788. Its totient is φ = 47284480.

The previous prime is 51981557. The next prime is 51981581. The reversal of 51981563 is 36518915.

It is not a de Polignac number, because 51981563 - 2¹⁶ = 51916027 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (51981533) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 485756 + ... + 485862.

It is an arithmetic number, because the mean of its divisors is an integer number (3173766).

Almost surely, 2^51981563 is an apocalyptic number.

51981563 is a deficient number, since it is larger than the sum of its proper divisors (5146225).

51981563 is a wasteful number, since it uses less digits than its factorization.

51981563 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 223 (or 165 counting only the distinct ones).

The product of its digits is 32400, while the sum is 38.

The square root of 51981563 is about 7209.8240616537. The cubic root of 51981563 is about 373.2069974491.

The spelling of 51981563 in words is "fifty-one million, nine hundred eighty-one thousand, five hundred sixty-three".