21002020120 has 64 divisors (see below), whose sum is σ = 51346252800. Its totient is φ = 7701920640.

The previous prime is 21002020103. The next prime is 21002020163. The reversal of 21002020120 is 2102020012.

It is a Harshad number since it is a multiple of its sum of digits (10).

It is a junction number, because it is equal to n+sod(n) for n = 21002020097 and 21002020106.

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, 422154 + ... + 469273.

It is an arithmetic number, because the mean of its divisors is an integer number (802285200).

Almost surely, 2^21002020120 is an apocalyptic number.

21002020120 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21002020120 is an abundant number, since it is smaller than the sum of its proper divisors (30344232680).

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

21002020120 is a wasteful number, since it uses less digits than its factorization.

21002020120 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 891488 (or 891484 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 10.

Adding to 21002020120 its reverse (2102020012), we get a palindrome (23104040132).

The spelling of 21002020120 in words is "twenty-one billion, two million, twenty thousand, one hundred twenty".