21420078736 has 45 divisors (see below), whose sum is σ = 48286379619. Its totient is φ = 9178277472.

The previous prime is 21420078721. The next prime is 21420078817. The reversal of 21420078736 is 63787002412.

The square root of 21420078736 is 146356.

It is a perfect power (a square), and thus also a powerful number.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 4095355 + ... + 4100581.

Almost surely, 2^21420078736 is an apocalyptic number.

21420078736 is the 146356-th square number.

It is an amenable number.

21420078736 is an abundant number, since it is smaller than the sum of its proper divisors (26866300883).

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

21420078736 is an frugal number, since it uses more digits than its factorization.

21420078736 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10476 (or 5236 counting only the distinct ones).

The product of its (nonzero) digits is 112896, while the sum is 40.

The spelling of 21420078736 in words is "twenty-one billion, four hundred twenty million, seventy-eight thousand, seven hundred thirty-six".