21009922704 has 135 divisors (see below), whose sum is σ = 60310924297. Its totient is φ = 6827630592.

The previous prime is 21009922693. The next prime is 21009922709. The reversal of 21009922704 is 40722990012.

The square root of 21009922704 is 144948.

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

It can be written as a sum of positive squares in only one way, i.e., 20684192400 + 325730304 = 143820^2 + 18048^2 .

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21009922709) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 81750544 + ... + 81750800.

Almost surely, 2^21009922704 is an apocalyptic number.

21009922704 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

21009922704 is the 144948-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21009922704

21009922704 is an abundant number, since it is smaller than the sum of its proper divisors (39301001593).

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

21009922704 is an equidigital number, since it uses as much as digits as its factorization.

21009922704 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 622 (or 309 counting only the distinct ones).

The product of its (nonzero) digits is 18144, while the sum is 36.

Multiplying 21009922704 by its sum of digits (36), we get a square (756357217344 = 869688²).

21009922704 divided by its sum of digits (36) gives a square (583608964 = 24158²).

The spelling of 21009922704 in words is "twenty-one billion, nine million, nine hundred twenty-two thousand, seven hundred four".