15663664261 has 4 divisors (see below), whose sum is σ = 17901330592. Its totient is φ = 13425997932.

The previous prime is 15663664243. The next prime is 15663664273. The reversal of 15663664261 is 16246636651.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 15663664261 - 2²¹ = 15661567109 is a prime.

It is a super-2 number, since 2×15663664261² (a number of 21 digits) 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 (15663664661) 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, 1118833155 + ... + 1118833168.

It is an arithmetic number, because the mean of its divisors is an integer number (4475332648).

Almost surely, 2^15663664261 is an apocalyptic number.

It is an amenable number.

15663664261 is a deficient number, since it is larger than the sum of its proper divisors (2237666331).

15663664261 is an equidigital number, since it uses as much as digits as its factorization.

15663664261 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2237666330.

The product of its digits is 933120, while the sum is 46.

The spelling of 15663664261 in words is "fifteen billion, six hundred sixty-three million, six hundred sixty-four thousand, two hundred sixty-one".