21702091720 has 64 divisors (see below), whose sum is σ = 49027680000. Its totient is φ = 8645726208.

The previous prime is 21702091699. The next prime is 21702091729. The reversal of 21702091720 is 2719020712.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (21702091729) 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, 18659859 + ... + 18661021.

It is an arithmetic number, because the mean of its divisors is an integer number (766057500).

Almost surely, 2^21702091720 is an apocalyptic number.

21702091720 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21702091720 is an abundant number, since it is smaller than the sum of its proper divisors (27325588280).

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

21702091720 is a wasteful number, since it uses less digits than its factorization.

21702091720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2662 (or 2658 counting only the distinct ones).

The product of its (nonzero) digits is 3528, while the sum is 31.

The spelling of 21702091720 in words is "twenty-one billion, seven hundred two million, ninety-one thousand, seven hundred twenty".