15661651 has 2 divisors, whose sum is σ = 15661652. Its totient is φ = 15661650.

The previous prime is 15661637. The next prime is 15661661. The reversal of 15661651 is 15616651.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 15661651 - 2¹⁹ = 15137363 is a prime.

It is not a weakly prime, because it can be changed into another prime (15661601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7830825 + 7830826.

It is an arithmetic number, because the mean of its divisors is an integer number (7830826).

Almost surely, 2^15661651 is an apocalyptic number.

15661651 is a deficient number, since it is larger than the sum of its proper divisors (1).

15661651 is an equidigital number, since it uses as much as digits as its factorization.

15661651 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5400, while the sum is 31.

The square root of 15661651 is about 3957.4803852957. The cubic root of 15661651 is about 250.1953193616.

The spelling of 15661651 in words is "fifteen million, six hundred sixty-one thousand, six hundred fifty-one".