51871813 has 4 divisors (see below), whose sum is σ = 59282080. Its totient is φ = 44461548.

The previous prime is 51871769. The next prime is 51871823. The reversal of 51871813 is 31817815.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-51871813 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 (51871823) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3705123 + ... + 3705136.

It is an arithmetic number, because the mean of its divisors is an integer number (14820520).

Almost surely, 2^51871813 is an apocalyptic number.

It is an amenable number.

51871813 is a deficient number, since it is larger than the sum of its proper divisors (7410267).

51871813 is an equidigital number, since it uses as much as digits as its factorization.

51871813 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7410266.

The product of its digits is 6720, while the sum is 34.

The square root of 51871813 is about 7202.2088972759. The cubic root of 51871813 is about 372.9441585647.

The spelling of 51871813 in words is "fifty-one million, eight hundred seventy-one thousand, eight hundred thirteen".