21009869940 has 48 divisors (see below), whose sum is σ = 60725306880. Its totient is φ = 5421901440.

The previous prime is 21009869939. The next prime is 21009869977. The reversal of 21009869940 is 4996890012.

It is a self number, because there is not a number n which added to its sum of digits gives 21009869940.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5645955 + ... + 5649674.

It is an arithmetic number, because the mean of its divisors is an integer number (1265110560).

Almost surely, 2^21009869940 is an apocalyptic number.

21009869940 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21009869940 is an abundant number, since it is smaller than the sum of its proper divisors (39715436940).

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

21009869940 is a wasteful number, since it uses less digits than its factorization.

21009869940 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11295672 (or 11295670 counting only the distinct ones).

The product of its (nonzero) digits is 279936, while the sum is 48.

The spelling of 21009869940 in words is "twenty-one billion, nine million, eight hundred sixty-nine thousand, nine hundred forty".