21210091845720 has 64 divisors (see below), whose sum is σ = 65350012727520. Its totient is φ = 5503158964224.

The previous prime is 21210091845671. The next prime is 21210091845727. The reversal of 21210091845720 is 2754819001212.

It is a super-2 number, since 2×21210091845720² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21210091845727) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2388519417 + ... + 2388528296.

Almost surely, 2^{21210091845720} is an apocalyptic number.

21210091845720 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21210091845720 is an abundant number, since it is smaller than the sum of its proper divisors (44139920881800).

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

21210091845720 is a wasteful number, since it uses less digits than its factorization.

21210091845720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4777047764 (or 4777047760 counting only the distinct ones).

The product of its (nonzero) digits is 80640, while the sum is 42.

The spelling of 21210091845720 in words is "twenty-one trillion, two hundred ten billion, ninety-one million, eight hundred forty-five thousand, seven hundred twenty".