21692587644 has 168 divisors, whose sum is σ = 70052556000. Its totient is φ = 5721052032.

The previous prime is 21692587607. The next prime is 21692587649. The reversal of 21692587644 is 44678529612.

21692587644 is a `hidden beast` number, since 2 + 16 + 9 + 2 + 587 + 6 + 44 = 666.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21692587649) by changing a digit.

It is a polite number, since it can be written in 55 ways as a sum of consecutive naturals, for example, 224482 + ... + 306230.

It is an arithmetic number, because the mean of its divisors is an integer number (416979500).

Almost surely, 2^21692587644 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 21692587644, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35026278000).

21692587644 is an abundant number, since it is smaller than the sum of its proper divisors (48359968356).

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

21692587644 is a wasteful number, since it uses less digits than its factorization.

21692587644 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 81791 (or 81774 counting only the distinct ones).

The product of its digits is 5806080, while the sum is 54.

The spelling of 21692587644 in words is "twenty-one billion, six hundred ninety-two million, five hundred eighty-seven thousand, six hundred forty-four".