51981845 has 4 divisors (see below), whose sum is σ = 62378220. Its totient is φ = 41585472.

The previous prime is 51981827. The next prime is 51981877. The reversal of 51981845 is 54818915.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 29008996 + 22972849 = 5386^2 + 4793^2 .

It is a cyclic number.

It is not a de Polignac number, because 51981845 - 2¹⁰ = 51980821 is a prime.

It is a super-2 number, since 2×51981845² = 5404224419208050, which contains 22 as substring.

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, 5198180 + ... + 5198189.

It is an arithmetic number, because the mean of its divisors is an integer number (15594555).

Almost surely, 2^51981845 is an apocalyptic number.

It is an amenable number.

51981845 is a deficient number, since it is larger than the sum of its proper divisors (10396375).

51981845 is a wasteful number, since it uses less digits than its factorization.

51981845 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10396374.

The product of its digits is 57600, while the sum is 41.

The square root of 51981845 is about 7209.8436182763. The cubic root of 51981845 is about 373.2076723306.

The spelling of 51981845 in words is "fifty-one million, nine hundred eighty-one thousand, eight hundred forty-five".