21308943980 has 24 divisors (see below), whose sum is σ = 45416677488. Its totient is φ = 8396359488.

The previous prime is 21308943967. The next prime is 21308943983. The reversal of 21308943980 is 8934980312.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (21308943983) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7949759 + ... + 7952438.

It is an arithmetic number, because the mean of its divisors is an integer number (1892361562).

Almost surely, 2^21308943980 is an apocalyptic number.

21308943980 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21308943980 is an abundant number, since it is smaller than the sum of its proper divisors (24107733508).

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

21308943980 is a wasteful number, since it uses less digits than its factorization.

21308943980 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15902273 (or 15902271 counting only the distinct ones).

The product of its (nonzero) digits is 373248, while the sum is 47.

The spelling of 21308943980 in words is "twenty-one billion, three hundred eight million, nine hundred forty-three thousand, nine hundred eighty".