15661654561 has 16 divisors (see below), whose sum is σ = 17994912768. Its totient is φ = 13352446800.

The previous prime is 15661654531. The next prime is 15661654663. The reversal of 15661654561 is 16545616651.

It is not a de Polignac number, because 15661654561 - 2⁵ = 15661654529 is a prime.

It is not an unprimeable number, because it can be changed into a prime (15661654501) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4711446 + ... + 4714768.

It is an arithmetic number, because the mean of its divisors is an integer number (1124682048).

Almost surely, 2^15661654561 is an apocalyptic number.

It is an amenable number.

15661654561 is a deficient number, since it is larger than the sum of its proper divisors (2333258207).

15661654561 is a wasteful number, since it uses less digits than its factorization.

15661654561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6732.

The product of its digits is 648000, while the sum is 46.

The spelling of 15661654561 in words is "fifteen billion, six hundred sixty-one million, six hundred fifty-four thousand, five hundred sixty-one".