21069890640 has 80 divisors (see below), whose sum is σ = 72574075200. Its totient is φ = 5618636928.

The previous prime is 21069890563. The next prime is 21069890657. The reversal of 21069890640 is 4609896012.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (80).

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 15 ways as a sum of consecutive naturals, for example, 4875130 + ... + 4879449.

It is an arithmetic number, because the mean of its divisors is an integer number (907175940).

Almost surely, 2^21069890640 is an apocalyptic number.

21069890640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21069890640 is an abundant number, since it is smaller than the sum of its proper divisors (51504184560).

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

21069890640 is a wasteful number, since it uses less digits than its factorization.

21069890640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9754601 (or 9754589 counting only the distinct ones).

The product of its (nonzero) digits is 186624, while the sum is 45.

The spelling of 21069890640 in words is "twenty-one billion, sixty-nine million, eight hundred ninety thousand, six hundred forty".