51565421 has 4 divisors (see below), whose sum is σ = 51584700. Its totient is φ = 51546144.

The previous prime is 51565391. The next prime is 51565427. The reversal of 51565421 is 12456515.

It is a happy number.

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

It can be written as a sum of positive squares in 2 ways, for example, as 20884900 + 30680521 = 4570^2 + 5539^2 .

It is a cyclic number.

It is not a de Polignac number, because 51565421 - 2⁶ = 51565357 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51565427) 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, 4826 + ... + 11243.

It is an arithmetic number, because the mean of its divisors is an integer number (12896175).

Almost surely, 2^51565421 is an apocalyptic number.

It is an amenable number.

51565421 is a deficient number, since it is larger than the sum of its proper divisors (19279).

51565421 is a wasteful number, since it uses less digits than its factorization.

51565421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19278.

The product of its digits is 6000, while the sum is 29.

The square root of 51565421 is about 7180.9066976253. The cubic root of 51565421 is about 372.2084164710.

The spelling of 51565421 in words is "fifty-one million, five hundred sixty-five thousand, four hundred twenty-one".