21139940640 has 960 divisors, whose sum is σ = 89648850816. Its totient is φ = 4147347456.

The previous prime is 21139940617. The next prime is 21139940651. The reversal of 21139940640 is 4604993112.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is an unprimeable number.

It is a polite number, since it can be written in 159 ways as a sum of consecutive naturals, for example, 254698039 + ... + 254698121.

Almost surely, 2^21139940640 is an apocalyptic number.

21139940640 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 21139940640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (44824425408).

21139940640 is an abundant number, since it is smaller than the sum of its proper divisors (68508910176).

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

21139940640 is a wasteful number, since it uses less digits than its factorization.

21139940640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 159 (or 130 counting only the distinct ones).

The product of its (nonzero) digits is 46656, while the sum is 39.

The spelling of 21139940640 in words is "twenty-one billion, one hundred thirty-nine million, nine hundred forty thousand, six hundred forty".