51397661 has 4 divisors (see below), whose sum is σ = 58740192. Its totient is φ = 44055132.

The previous prime is 51397639. The next prime is 51397669. The reversal of 51397661 is 16679315.

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 51397661 - 2¹⁰ = 51396637 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (51397669) 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, 3671255 + ... + 3671268.

It is an arithmetic number, because the mean of its divisors is an integer number (14685048).

Almost surely, 2^51397661 is an apocalyptic number.

It is an amenable number.

51397661 is a deficient number, since it is larger than the sum of its proper divisors (7342531).

51397661 is an equidigital number, since it uses as much as digits as its factorization.

51397661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7342530.

The product of its digits is 34020, while the sum is 38.

The square root of 51397661 is about 7169.2162054160. The cubic root of 51397661 is about 371.8043374058.

The spelling of 51397661 in words is "fifty-one million, three hundred ninety-seven thousand, six hundred sixty-one".