51691390 has 16 divisors (see below), whose sum is σ = 98518032. Its totient is φ = 19460224.

The previous prime is 51691363. The next prime is 51691391. The reversal of 51691390 is 9319615.

It is a Harshad number since it is a multiple of its sum of digits (34).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51691391) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 151864 + ... + 152203.

It is an arithmetic number, because the mean of its divisors is an integer number (6157377).

Almost surely, 2^51691390 is an apocalyptic number.

51691390 is a deficient number, since it is larger than the sum of its proper divisors (46826642).

51691390 is a wasteful number, since it uses less digits than its factorization.

51691390 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 304091.

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

The square root of 51691390 is about 7189.6724542916. The cubic root of 51691390 is about 372.5112589123.

The spelling of 51691390 in words is "fifty-one million, six hundred ninety-one thousand, three hundred ninety".