21326657940 has 192 divisors, whose sum is σ = 76031262720. Its totient is φ = 4861607040.

The previous prime is 21326657857. The next prime is 21326657987. The reversal of 21326657940 is 4975662312.

21326657940 is a `hidden beast` number, since 2 + 1 + 32 + 6 + 6 + 579 + 40 = 666.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 1440375 + ... + 1455105.

It is an arithmetic number, because the mean of its divisors is an integer number (395996160).

Almost surely, 2^21326657940 is an apocalyptic number.

21326657940 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21326657940, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38015631360).

21326657940 is an abundant number, since it is smaller than the sum of its proper divisors (54704604780).

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

21326657940 is a wasteful number, since it uses less digits than its factorization.

21326657940 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15139 (or 15131 counting only the distinct ones).

The product of its (nonzero) digits is 544320, while the sum is 45.

The spelling of 21326657940 in words is "twenty-one billion, three hundred twenty-six million, six hundred fifty-seven thousand, nine hundred forty".