21989540420 has 12 divisors (see below), whose sum is σ = 46178034924. Its totient is φ = 8795816160.

The previous prime is 21989540407. The next prime is 21989540473. The reversal of 21989540420 is 2404598912.

It can be written as a sum of positive squares in 2 ways, for example, as 7307856196 + 14681684224 = 85486^2 + 121168^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 549738491 + ... + 549738530.

It is an arithmetic number, because the mean of its divisors is an integer number (3848169577).

Almost surely, 2^21989540420 is an apocalyptic number.

21989540420 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21989540420 is an abundant number, since it is smaller than the sum of its proper divisors (24188494504).

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

21989540420 is a wasteful number, since it uses less digits than its factorization.

21989540420 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1099477030 (or 1099477028 counting only the distinct ones).

The product of its (nonzero) digits is 207360, while the sum is 44.

The spelling of 21989540420 in words is "twenty-one billion, nine hundred eighty-nine million, five hundred forty thousand, four hundred twenty".