51991045 has 4 divisors (see below), whose sum is σ = 62389260. Its totient is φ = 41592832.

The previous prime is 51991007. The next prime is 51991081. The reversal of 51991045 is 54019915.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 54019915 = 5 ⋅10803983.

It can be written as a sum of positive squares in 2 ways, for example, as 10233601 + 41757444 = 3199^2 + 6462^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-51991045 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 51991045.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5199100 + ... + 5199109.

It is an arithmetic number, because the mean of its divisors is an integer number (15597315).

Almost surely, 2^51991045 is an apocalyptic number.

It is an amenable number.

51991045 is a deficient number, since it is larger than the sum of its proper divisors (10398215).

51991045 is a wasteful number, since it uses less digits than its factorization.

51991045 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10398214.

The product of its (nonzero) digits is 8100, while the sum is 34.

The square root of 51991045 is about 7210.4816066612. The cubic root of 51991045 is about 373.2296884020.

The spelling of 51991045 in words is "fifty-one million, nine hundred ninety-one thousand, forty-five".