51645647 has 4 divisors (see below), whose sum is σ = 51692760. Its totient is φ = 51598536.

The previous prime is 51645641. The next prime is 51645661. The reversal of 51645647 is 74654615.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 51645647 - 2⁴ = 51645631 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 51645647.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51645641) 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, 21872 + ... + 24117.

It is an arithmetic number, because the mean of its divisors is an integer number (12923190).

Almost surely, 2^51645647 is an apocalyptic number.

51645647 is a deficient number, since it is larger than the sum of its proper divisors (47113).

51645647 is a wasteful number, since it uses less digits than its factorization.

51645647 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 47112.

The product of its digits is 100800, while the sum is 38.

The square root of 51645647 is about 7186.4905899890. The cubic root of 51645647 is about 372.4013449834.

The spelling of 51645647 in words is "fifty-one million, six hundred forty-five thousand, six hundred forty-seven".