51090691 has 4 divisors (see below), whose sum is σ = 51105384. Its totient is φ = 51076000.

The previous prime is 51090679. The next prime is 51090707. The reversal of 51090691 is 19609015.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a 5-Lehmer number, since φ(51090691) divides (51090691-1)⁵.

It is a cyclic number.

It is not a de Polignac number, because 51090691 - 2¹¹ = 51088643 is a prime.

It is a super-2 number, since 2×51090691² = 5220517413714962, which contains 22 as substring.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (51090671) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1131 + ... + 10171.

It is an arithmetic number, because the mean of its divisors is an integer number (12776346).

Almost surely, 2^51090691 is an apocalyptic number.

51090691 is a deficient number, since it is larger than the sum of its proper divisors (14693).

51090691 is an equidigital number, since it uses as much as digits as its factorization.

51090691 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14692.

The product of its (nonzero) digits is 2430, while the sum is 31.

The square root of 51090691 is about 7147.7752482853. The cubic root of 51090691 is about 371.0626645384.

The spelling of 51090691 in words is "fifty-one million, ninety thousand, six hundred ninety-one".