21738821620 has 24 divisors (see below), whose sum is σ = 45890546688. Its totient is φ = 8650000800.

The previous prime is 21738821617. The next prime is 21738821627. The reversal of 21738821620 is 2612883712.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21738821627) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2841576 + ... + 2849215.

It is an arithmetic number, because the mean of its divisors is an integer number (1912106112).

Almost surely, 2^21738821620 is an apocalyptic number.

21738821620 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21738821620 is an abundant number, since it is smaller than the sum of its proper divisors (24151725068).

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

21738821620 is a wasteful number, since it uses less digits than its factorization.

21738821620 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5690991 (or 5690989 counting only the distinct ones).

The product of its (nonzero) digits is 64512, while the sum is 40.

The spelling of 21738821620 in words is "twenty-one billion, seven hundred thirty-eight million, eight hundred twenty-one thousand, six hundred twenty".