51091639 has 2 divisors, whose sum is σ = 51091640. Its totient is φ = 51091638.

The previous prime is 51091637. The next prime is 51091643. The reversal of 51091639 is 93619015.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 51091639 - 2¹ = 51091637 is a prime.

It is a super-2 number, since 2×51091639² = 5220711151412642, which contains 22 as substring.

Together with 51091637, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (51091631) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25545819 + 25545820.

It is an arithmetic number, because the mean of its divisors is an integer number (25545820).

Almost surely, 2^51091639 is an apocalyptic number.

51091639 is a deficient number, since it is larger than the sum of its proper divisors (1).

51091639 is an equidigital number, since it uses as much as digits as its factorization.

51091639 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 7290, while the sum is 34.

The square root of 51091639 is about 7147.8415623180. The cubic root of 51091639 is about 371.0649595764.

The spelling of 51091639 in words is "fifty-one million, ninety-one thousand, six hundred thirty-nine".