51661613 has 2 divisors, whose sum is σ = 51661614. Its totient is φ = 51661612.

The previous prime is 51661609. The next prime is 51661637. The reversal of 51661613 is 31616615.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 31393609 + 20268004 = 5603^2 + 4502^2 .

It is a cyclic number.

It is not a de Polignac number, because 51661613 - 2² = 51661609 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (51660613) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25830806 + 25830807.

It is an arithmetic number, because the mean of its divisors is an integer number (25830807).

Almost surely, 2^51661613 is an apocalyptic number.

It is an amenable number.

51661613 is a deficient number, since it is larger than the sum of its proper divisors (1).

51661613 is an equidigital number, since it uses as much as digits as its factorization.

51661613 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3240, while the sum is 29.

The square root of 51661613 is about 7187.6013384160. The cubic root of 51661613 is about 372.4397163830.

The spelling of 51661613 in words is "fifty-one million, six hundred sixty-one thousand, six hundred thirteen".