51999991 has 8 divisors (see below), whose sum is σ = 55145664. Its totient is φ = 48864000.

The previous prime is 51999971. The next prime is 52000007. The reversal of 51999991 is 19999915.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 51999991 - 2²³ = 43611383 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51999971) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10731 + ... + 14803.

It is an arithmetic number, because the mean of its divisors is an integer number (6893208).

Almost surely, 2^51999991 is an apocalyptic number.

51999991 is a deficient number, since it is larger than the sum of its proper divisors (3145673).

51999991 is a wasteful number, since it uses less digits than its factorization.

51999991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4841.

The product of its digits is 295245, while the sum is 52.

The square root of 51999991 is about 7211.1019268902. The cubic root of 51999991 is about 373.2510941480.

The spelling of 51999991 in words is "fifty-one million, nine hundred ninety-nine thousand, nine hundred ninety-one".