51509979 has 16 divisors (see below), whose sum is σ = 77936640. Its totient is φ = 33608520.

The previous prime is 51509971. The next prime is 51509987. The reversal of 51509979 is 97990515.

51509979 is a `hidden beast` number, since 51 + 509 + 97 + 9 = 666.

It is an interprime number because it is at equal distance from previous prime (51509971) and next prime (51509987).

It is not a de Polignac number, because 51509979 - 2³ = 51509971 is a prime.

It is not an unprimeable number, because it can be changed into a prime (51509971) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 19027 + ... + 21564.

It is an arithmetic number, because the mean of its divisors is an integer number (4871040).

Almost surely, 2^51509979 is an apocalyptic number.

51509979 is a deficient number, since it is larger than the sum of its proper divisors (26426661).

51509979 is a wasteful number, since it uses less digits than its factorization.

51509979 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40647 (or 40641 counting only the distinct ones).

The product of its (nonzero) digits is 127575, while the sum is 45.

The square root of 51509979 is about 7177.0452834018. The cubic root of 51509979 is about 372.0749718821.

It can be divided in two parts, 5150 and 9979, that added together give a square (15129 = 123²).

The spelling of 51509979 in words is "fifty-one million, five hundred nine thousand, nine hundred seventy-nine".