21021110120020 has 48 divisors (see below), whose sum is σ = 44307008596368. Its totient is φ = 8377473459200.

The previous prime is 21021110120011. The next prime is 21021110120047. The reversal of 21021110120020 is 2002101112012.

It can be written as a sum of positive squares in 8 ways, for example, as 3856180528656 + 17164929591364 = 1963716^2 + 4143058^2 .

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, 21203232 + ... + 22172488.

It is an arithmetic number, because the mean of its divisors is an integer number (923062679091).

Almost surely, 2^{21021110120020} is an apocalyptic number.

21021110120020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21021110120020 is an abundant number, since it is smaller than the sum of its proper divisors (23285898476348).

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

21021110120020 is a wasteful number, since it uses less digits than its factorization.

21021110120020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 973260 (or 973258 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 13.

Adding to 21021110120020 its reverse (2002101112012), we get a palindrome (23023211232032).

The spelling of 21021110120020 in words is "twenty-one trillion, twenty-one billion, one hundred ten million, one hundred twenty thousand, twenty".