51639816 has 16 divisors (see below), whose sum is σ = 129099600. Its totient is φ = 17213264.

The previous prime is 51639811. The next prime is 51639823. The reversal of 51639816 is 61893615.

It is not an unprimeable number, because it can be changed into a prime (51639811) 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, 1075806 + ... + 1075853.

It is an arithmetic number, because the mean of its divisors is an integer number (8068725).

Almost surely, 2^51639816 is an apocalyptic number.

It is an amenable number.

51639816 is an abundant number, since it is smaller than the sum of its proper divisors (77459784).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

51639816 is a wasteful number, since it uses less digits than its factorization.

51639816 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2151668 (or 2151664 counting only the distinct ones).

The product of its digits is 38880, while the sum is 39.

The square root of 51639816 is about 7186.0848867794. The cubic root of 51639816 is about 372.3873292557.

The spelling of 51639816 in words is "fifty-one million, six hundred thirty-nine thousand, eight hundred sixteen".