21668859420 has 48 divisors (see below), whose sum is σ = 65339947680. Its totient is φ = 5333872896.

The previous prime is 21668859403. The next prime is 21668859431. The reversal of 21668859420 is 2495886612.

It is a happy number.

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, 13889515 + ... + 13891074.

It is an arithmetic number, because the mean of its divisors is an integer number (1361248910).

Almost surely, 2^21668859420 is an apocalyptic number.

21668859420 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21668859420 is an abundant number, since it is smaller than the sum of its proper divisors (43671088260).

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

21668859420 is a wasteful number, since it uses less digits than its factorization.

21668859420 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27780614 (or 27780612 counting only the distinct ones).

The product of its (nonzero) digits is 1658880, while the sum is 51.

The spelling of 21668859420 in words is "twenty-one billion, six hundred sixty-eight million, eight hundred fifty-nine thousand, four hundred twenty".