51639515 has 4 divisors (see below), whose sum is σ = 61967424. Its totient is φ = 41311608.

The previous prime is 51639509. The next prime is 51639551. The reversal of 51639515 is 51593615.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 51593615 = 5 ⋅10318723.

It is a cyclic number.

It is not a de Polignac number, because 51639515 - 2¹⁰ = 51638491 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5163947 + ... + 5163956.

It is an arithmetic number, because the mean of its divisors is an integer number (15491856).

Almost surely, 2^51639515 is an apocalyptic number.

51639515 is a deficient number, since it is larger than the sum of its proper divisors (10327909).

51639515 is a wasteful number, since it uses less digits than its factorization.

51639515 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10327908.

The product of its digits is 20250, while the sum is 35.

The square root of 51639515 is about 7186.0639434951. The cubic root of 51639515 is about 372.3866057261.

The spelling of 51639515 in words is "fifty-one million, six hundred thirty-nine thousand, five hundred fifteen".