21447294720 has 72 divisors (see below), whose sum is σ = 68497309776. Its totient is φ = 5719277568.

The previous prime is 21447294719. The next prime is 21447294763. The reversal of 21447294720 is 2749274412.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2788777 + ... + 2796456.

Almost surely, 2^21447294720 is an apocalyptic number.

21447294720 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21447294720 is an abundant number, since it is smaller than the sum of its proper divisors (47050015056).

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

21447294720 is an equidigital number, since it uses as much as digits as its factorization.

21447294720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5585257 (or 5585243 counting only the distinct ones).

The product of its (nonzero) digits is 225792, while the sum is 42.

The spelling of 21447294720 in words is "twenty-one billion, four hundred forty-seven million, two hundred ninety-four thousand, seven hundred twenty".