21420621860 has 96 divisors (see below), whose sum is σ = 52111382400. Its totient is φ = 7309670400.

The previous prime is 21420621853. The next prime is 21420621863. The reversal of 21420621860 is 6812602412.

It is not an unprimeable number, because it can be changed into a prime (21420621863) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1297055 + ... + 1313465.

It is an arithmetic number, because the mean of its divisors is an integer number (542826900).

Almost surely, 2^21420621860 is an apocalyptic number.

21420621860 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21420621860, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26055691200).

21420621860 is an abundant number, since it is smaller than the sum of its proper divisors (30690760540).

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

21420621860 is a wasteful number, since it uses less digits than its factorization.

21420621860 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16797 (or 16795 counting only the distinct ones).

The product of its (nonzero) digits is 9216, while the sum is 32.

The spelling of 21420621860 in words is "twenty-one billion, four hundred twenty million, six hundred twenty-one thousand, eight hundred sixty".