21045458640 has 80 divisors (see below), whose sum is σ = 65341317888. Its totient is φ = 5603486208.

The previous prime is 21045458633. The next prime is 21045458657. The reversal of 21045458640 is 4685454012.

It is a happy number.

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

It is a super-2 number, since 2×21045458640² (a number of 21 digits) contains 22 as substring.

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, 89577 + ... + 223863.

Almost surely, 2^21045458640 is an apocalyptic number.

21045458640 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 21045458640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32670658944).

21045458640 is an abundant number, since it is smaller than the sum of its proper divisors (44295859248).

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

21045458640 is a wasteful number, since it uses less digits than its factorization.

21045458640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 134956 (or 134950 counting only the distinct ones).

The product of its (nonzero) digits is 153600, while the sum is 39.

The spelling of 21045458640 in words is "twenty-one billion, forty-five million, four hundred fifty-eight thousand, six hundred forty".