21020121220020 has 48 divisors (see below), whose sum is σ = 63383750142720. Its totient is φ = 5174183684736.

The previous prime is 21020121220009. The next prime is 21020121220027. The reversal of 21020121220020 is 2002212102012.

It is a super-2 number, since 2×21020121220020² (a number of 27 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21020121220027) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 13474435900 + ... + 13474437459.

It is an arithmetic number, because the mean of its divisors is an integer number (1320494794640).

Almost surely, 2^{21020121220020} is an apocalyptic number.

21020121220020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21020121220020 is an abundant number, since it is smaller than the sum of its proper divisors (42363628922700).

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

21020121220020 is a wasteful number, since it uses less digits than its factorization.

21020121220020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26948873384 (or 26948873382 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 15.

Adding to 21020121220020 its reverse (2002212102012), we get a palindrome (23022333322032).

The spelling of 21020121220020 in words is "twenty-one trillion, twenty billion, one hundred twenty-one million, two hundred twenty thousand, twenty".