51661621 has 8 divisors (see below), whose sum is σ = 56476224. Its totient is φ = 46866720.

The previous prime is 51661613. The next prime is 51661637. The reversal of 51661621 is 12616615.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 51661621 - 2³ = 51661613 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 51661621.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51661651) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 865 + ... + 10201.

It is an arithmetic number, because the mean of its divisors is an integer number (7059528).

Almost surely, 2^51661621 is an apocalyptic number.

It is an amenable number.

51661621 is a deficient number, since it is larger than the sum of its proper divisors (4814603).

51661621 is a wasteful number, since it uses less digits than its factorization.

51661621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9851.

The product of its digits is 2160, while the sum is 28.

The square root of 51661621 is about 7187.6018949299. The cubic root of 51661621 is about 372.4397356076.

The spelling of 51661621 in words is "fifty-one million, six hundred sixty-one thousand, six hundred twenty-one".