21639923140 has 36 divisors (see below), whose sum is σ = 49950671148. Its totient is φ = 7869062080.

The previous prime is 21639923131. The next prime is 21639923167. The reversal of 21639923140 is 4132993612.

It can be written as a sum of positive squares in 2 ways, for example, as 16343576964 + 5296346176 = 127842^2 + 72776^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21639923093 and 21639923102.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 4468639 + ... + 4473478.

It is an arithmetic number, because the mean of its divisors is an integer number (1387518643).

Almost surely, 2^21639923140 is an apocalyptic number.

21639923140 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21639923140 is an abundant number, since it is smaller than the sum of its proper divisors (28310748008).

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

21639923140 is a wasteful number, since it uses less digits than its factorization.

21639923140 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8942148 (or 8942135 counting only the distinct ones).

The product of its (nonzero) digits is 69984, while the sum is 40.

The spelling of 21639923140 in words is "twenty-one billion, six hundred thirty-nine million, nine hundred twenty-three thousand, one hundred forty".