21185818608 has 80 divisors (see below), whose sum is σ = 59297204736. Its totient is φ = 6491950080.

The previous prime is 21185818571. The next prime is 21185818649. The reversal of 21185818608 is 80681858112.

It is a Harshad number since it is a multiple of its sum of digits (48).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 266808 + ... + 336983.

Almost surely, 2^21185818608 is an apocalyptic number.

It is an amenable number.

21185818608 is an abundant number, since it is smaller than the sum of its proper divisors (38111386128).

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

21185818608 is a wasteful number, since it uses less digits than its factorization.

21185818608 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 603862 (or 603856 counting only the distinct ones).

The product of its (nonzero) digits is 245760, while the sum is 48.

The spelling of 21185818608 in words is "twenty-one billion, one hundred eighty-five million, eight hundred eighteen thousand, six hundred eight".