21371235840 has 240 divisors, whose sum is σ = 78369836688. Its totient is φ = 5363662848.

The previous prime is 21371235829. The next prime is 21371235889. The reversal of 21371235840 is 4853217312.

21371235840 is a `hidden beast` number, since 2 + 1 + 3 + 71 + 2 + 3 + 584 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (240).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 21371235795 and 21371235804.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 364399 + ... + 418961.

Almost surely, 2^21371235840 is an apocalyptic number.

21371235840 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 21371235840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39184918344).

21371235840 is an abundant number, since it is smaller than the sum of its proper divisors (56998600848).

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

21371235840 is a wasteful number, since it uses less digits than its factorization.

21371235840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 54609 (or 54590 counting only the distinct ones).

The product of its (nonzero) digits is 40320, while the sum is 36.

The spelling of 21371235840 in words is "twenty-one billion, three hundred seventy-one million, two hundred thirty-five thousand, eight hundred forty".