15555961 has 2 divisors, whose sum is σ = 15555962. Its totient is φ = 15555960.

The previous prime is 15555949. The next prime is 15555971. The reversal of 15555961 is 16955551.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13542400 + 2013561 = 3680^2 + 1419^2 .

It is a cyclic number.

It is not a de Polignac number, because 15555961 - 2⁵ = 15555929 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 15555961.

It is not a weakly prime, because it can be changed into another prime (15555931) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7777980 + 7777981.

It is an arithmetic number, because the mean of its divisors is an integer number (7777981).

Almost surely, 2^15555961 is an apocalyptic number.

It is an amenable number.

15555961 is a deficient number, since it is larger than the sum of its proper divisors (1).

15555961 is an equidigital number, since it uses as much as digits as its factorization.

15555961 is an evil number, because the sum of its binary digits is even.

The product of its digits is 33750, while the sum is 37.

The square root of 15555961 is about 3944.1045878628. The cubic root of 15555961 is about 249.6312483563.

The spelling of 15555961 in words is "fifteen million, five hundred fifty-five thousand, nine hundred sixty-one".