21436516720 has 20 divisors (see below), whose sum is σ = 49839901560. Its totient is φ = 8574606656.

The previous prime is 21436516697. The next prime is 21436516753. The reversal of 21436516720 is 2761563412.

It is a tau number, because it is divible by the number of its divisors (20).

It is a self number, because there is not a number n which added to its sum of digits gives 21436516720.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 133978150 + ... + 133978309.

It is an arithmetic number, because the mean of its divisors is an integer number (2491995078).

Almost surely, 2^21436516720 is an apocalyptic number.

21436516720 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21436516720 is an abundant number, since it is smaller than the sum of its proper divisors (28403384840).

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

21436516720 is a wasteful number, since it uses less digits than its factorization.

21436516720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 267956472 (or 267956466 counting only the distinct ones).

The product of its (nonzero) digits is 60480, while the sum is 37.

The spelling of 21436516720 in words is "twenty-one billion, four hundred thirty-six million, five hundred sixteen thousand, seven hundred twenty".