51660991 has 8 divisors (see below), whose sum is σ = 53557200. Its totient is φ = 49791168.

The previous prime is 51660979. The next prime is 51661003. The reversal of 51660991 is 19906615.

51660991 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (51660979) and next prime (51661003).

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 51660991 - 2⁷ = 51660863 is a prime.

It is a super-2 number, since 2×51660991² = 5337715982204162, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (37).

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 51660991.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51660901) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2566 + ... + 10483.

It is an arithmetic number, because the mean of its divisors is an integer number (6694650).

Almost surely, 2^51660991 is an apocalyptic number.

51660991 is a deficient number, since it is larger than the sum of its proper divisors (1896209).

51660991 is a wasteful number, since it uses less digits than its factorization.

51660991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13193.

The product of its (nonzero) digits is 14580, while the sum is 37.

The square root of 51660991 is about 7187.5580693306. The cubic root of 51660991 is about 372.4382216662.

The spelling of 51660991 in words is "fifty-one million, six hundred sixty thousand, nine hundred ninety-one".