21497419836 has 144 divisors (see below), whose sum is σ = 59637876480. Its totient is φ = 6499860480.

The previous prime is 21497419799. The next prime is 21497419843. The reversal of 21497419836 is 63891479412.

21497419836 is a `hidden beast` number, since 2 + 149 + 7 + 419 + 83 + 6 = 666.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 4873600 + ... + 4878008.

It is an arithmetic number, because the mean of its divisors is an integer number (414151920).

Almost surely, 2^21497419836 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21497419836, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29818938240).

21497419836 is an abundant number, since it is smaller than the sum of its proper divisors (38140456644).

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

21497419836 is a wasteful number, since it uses less digits than its factorization.

21497419836 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4724 (or 4719 counting only the distinct ones).

The product of its digits is 2612736, while the sum is 54.

The spelling of 21497419836 in words is "twenty-one billion, four hundred ninety-seven million, four hundred nineteen thousand, eight hundred thirty-six".