51640261 has 4 divisors (see below), whose sum is σ = 51655212. Its totient is φ = 51625312.

The previous prime is 51640243. The next prime is 51640289. The reversal of 51640261 is 16204615.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 6280036 + 45360225 = 2506^2 + 6735^2 .

It is a cyclic number.

It is not a de Polignac number, because 51640261 - 2⁵ = 51640229 is a prime.

It is a super-2 number, since 2×51640261² = 5333433112296242, 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 (51643261) 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, 651 + ... + 10183.

It is an arithmetic number, because the mean of its divisors is an integer number (12913803).

Almost surely, 2^51640261 is an apocalyptic number.

It is an amenable number.

51640261 is a deficient number, since it is larger than the sum of its proper divisors (14951).

51640261 is an equidigital number, since it uses as much as digits as its factorization.

51640261 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14950.

The product of its (nonzero) digits is 1440, while the sum is 25.

The square root of 51640261 is about 7186.1158493306. The cubic root of 51640261 is about 372.3883989205.

Adding to 51640261 its reverse (16204615), we get a palindrome (67844876).

The spelling of 51640261 in words is "fifty-one million, six hundred forty thousand, two hundred sixty-one".