51396781 has 4 divisors (see below), whose sum is σ = 51455872. Its totient is φ = 51337692.

The previous prime is 51396769. The next prime is 51396809. The reversal of 51396781 is 18769315.

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 not a de Polignac number, because 51396781 - 2⁹ = 51396269 is a prime.

It is a super-2 number, since 2×51396781² = 5283258194323922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51396721) 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, 28221 + ... + 29986.

It is an arithmetic number, because the mean of its divisors is an integer number (12863968).

Almost surely, 2^51396781 is an apocalyptic number.

It is an amenable number.

51396781 is a deficient number, since it is larger than the sum of its proper divisors (59091).

51396781 is an equidigital number, since it uses as much as digits as its factorization.

51396781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 59090.

The product of its digits is 45360, while the sum is 40.

The square root of 51396781 is about 7169.1548316381. The cubic root of 51396781 is about 371.8022154566.

The spelling of 51396781 in words is "fifty-one million, three hundred ninety-six thousand, seven hundred eighty-one".