51891381 has 16 divisors (see below), whose sum is σ = 80219520. Its totient is φ = 33089760.

The previous prime is 51891349. The next prime is 51891383. The reversal of 51891381 is 18319815.

51891381 is a `hidden beast` number, since 518 + 9 + 138 + 1 = 666.

It is not a de Polignac number, because 51891381 - 2⁵ = 51891349 is a prime.

It is a super-2 number, since 2×51891381² = 5385430844174322, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51891383) 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, 41160 + ... + 42401.

It is an arithmetic number, because the mean of its divisors is an integer number (5013720).

Almost surely, 2^51891381 is an apocalyptic number.

It is an amenable number.

51891381 is a deficient number, since it is larger than the sum of its proper divisors (28328139).

51891381 is a wasteful number, since it uses less digits than its factorization.

51891381 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 83593 (or 83587 counting only the distinct ones).

The product of its digits is 8640, while the sum is 36.

The square root of 51891381 is about 7203.5672413048. The cubic root of 51891381 is about 372.9910488596.

The spelling of 51891381 in words is "fifty-one million, eight hundred ninety-one thousand, three hundred eighty-one".