11921817564 has 18 divisors (see below), whose sum is σ = 30135705600. Its totient is φ = 3973939176.

The previous prime is 11921817547. The next prime is 11921817587. The reversal of 11921817564 is 46571812911.

11921817564 is a `hidden beast` number, since 1 + 1 + 9 + 2 + 1 + 81 + 7 + 564 = 666.

It is a tau number, because it is divible by the number of its divisors (18).

It is a super-3 number, since 3×11921817564³ (a number of 31 digits) contains 333 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 165580764 + ... + 165580835.

Almost surely, 2^11921817564 is an apocalyptic number.

It is an amenable number.

11921817564 is an abundant number, since it is smaller than the sum of its proper divisors (18213888036).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

11921817564 is a wasteful number, since it uses less digits than its factorization.

11921817564 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 331161609 (or 331161604 counting only the distinct ones).

The product of its digits is 120960, while the sum is 45.

The spelling of 11921817564 in words is "eleven billion, nine hundred twenty-one million, eight hundred seventeen thousand, five hundred sixty-four".