21003836640 has 48 divisors (see below), whose sum is σ = 66162086928. Its totient is φ = 5601022976.

The previous prime is 21003836599. The next prime is 21003836663. The reversal of 21003836640 is 4663830012.

It is a tau number, because it is divible by the number of its divisors (48).

It is a super-2 number, since 2×21003836640² (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 7 ways as a sum of consecutive naturals, for example, 21878517 + ... + 21879476.

It is an arithmetic number, because the mean of its divisors is an integer number (1378376811).

Almost surely, 2^21003836640 is an apocalyptic number.

21003836640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21003836640 is an abundant number, since it is smaller than the sum of its proper divisors (45158250288).

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

21003836640 is a wasteful number, since it uses less digits than its factorization.

21003836640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43758011 (or 43758003 counting only the distinct ones).

The product of its (nonzero) digits is 20736, while the sum is 33.

The spelling of 21003836640 in words is "twenty-one billion, three million, eight hundred thirty-six thousand, six hundred forty".