21105726240 has 48 divisors (see below), whose sum is σ = 66483039168. Its totient is φ = 5628193536.

The previous prime is 21105726217. The next prime is 21105726241. The reversal of 21105726240 is 4262750112.

It is a tau number, because it is divible by the number of its divisors (48).

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 21105726198 and 21105726207.

It is not an unprimeable number, because it can be changed into a prime (21105726241) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 21984652 + ... + 21985611.

It is an arithmetic number, because the mean of its divisors is an integer number (1385063316).

Almost surely, 2^21105726240 is an apocalyptic number.

21105726240 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21105726240 is an abundant number, since it is smaller than the sum of its proper divisors (45377312928).

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

21105726240 is a wasteful number, since it uses less digits than its factorization.

21105726240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43970281 (or 43970273 counting only the distinct ones).

The product of its (nonzero) digits is 6720, while the sum is 30.

The spelling of 21105726240 in words is "twenty-one billion, one hundred five million, seven hundred twenty-six thousand, two hundred forty".