21449940020 has 18 divisors (see below), whose sum is σ = 45046249542. Its totient is φ = 8579714016.

The previous prime is 21449940013. The next prime is 21449940049. The reversal of 21449940020 is 2004994412.

It is a happy number.

It can be written as a sum of positive squares in 3 ways, for example, as 93624976 + 21356315044 = 9676^2 + 146138^2 .

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, 638606 + ... + 671354.

It is an arithmetic number, because the mean of its divisors is an integer number (2502569419).

Almost surely, 2^21449940020 is an apocalyptic number.

21449940020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21449940020 is an abundant number, since it is smaller than the sum of its proper divisors (23596309522).

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

21449940020 is an frugal number, since it uses more digits than its factorization.

21449940020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 65507 (or 32756 counting only the distinct ones).

The product of its (nonzero) digits is 20736, while the sum is 35.

The spelling of 21449940020 in words is "twenty-one billion, four hundred forty-nine million, nine hundred forty thousand, twenty".