51506391 has 16 divisors (see below), whose sum is σ = 69903360. Its totient is φ = 33727680.

The previous prime is 51506381. The next prime is 51506401. The reversal of 51506391 is 19360515.

It is an interprime number because it is at equal distance from previous prime (51506381) and next prime (51506401).

It is not a de Polignac number, because 51506391 - 2⁶ = 51506327 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51506381) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 104656 + ... + 105146.

It is an arithmetic number, because the mean of its divisors is an integer number (4368960).

Almost surely, 2^51506391 is an apocalyptic number.

51506391 is a deficient number, since it is larger than the sum of its proper divisors (18396969).

51506391 is a wasteful number, since it uses less digits than its factorization.

51506391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1046.

The product of its (nonzero) digits is 4050, while the sum is 30.

The square root of 51506391 is about 7176.7953154594. The cubic root of 51506391 is about 372.0663325464.

The spelling of 51506391 in words is "fifty-one million, five hundred six thousand, three hundred ninety-one".