21456252642 has 96 divisors (see below), whose sum is σ = 48811553280. Its totient is φ = 6276441600.

The previous prime is 21456252589. The next prime is 21456252647. The reversal of 21456252642 is 24625265412.

It is a self number, because there is not a number n which added to its sum of digits gives 21456252642.

It is not an unprimeable number, because it can be changed into a prime (21456252647) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 11454618 + ... + 11456490.

It is an arithmetic number, because the mean of its divisors is an integer number (508453680).

Almost surely, 2^21456252642 is an apocalyptic number.

21456252642 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 21456252642, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24405776640).

21456252642 is an abundant number, since it is smaller than the sum of its proper divisors (27355300638).

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

21456252642 is a wasteful number, since it uses less digits than its factorization.

21456252642 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2440 (or 2429 counting only the distinct ones).

The product of its digits is 230400, while the sum is 39.

The spelling of 21456252642 in words is "twenty-one billion, four hundred fifty-six million, two hundred fifty-two thousand, six hundred forty-two".