21806974644 has 96 divisors (see below), whose sum is σ = 62674026240. Its totient is φ = 5746802688.

The previous prime is 21806974591. The next prime is 21806974649. The reversal of 21806974644 is 44647960812.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21806974649) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1531542 + ... + 1545714.

It is an arithmetic number, because the mean of its divisors is an integer number (652854440).

Almost surely, 2^21806974644 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 21806974644, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31337013120).

21806974644 is an abundant number, since it is smaller than the sum of its proper divisors (40867051596).

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

21806974644 is a wasteful number, since it uses less digits than its factorization.

21806974644 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15609 (or 15607 counting only the distinct ones).

The product of its (nonzero) digits is 2322432, while the sum is 51.

The spelling of 21806974644 in words is "twenty-one billion, eight hundred six million, nine hundred seventy-four thousand, six hundred forty-four".