21421020020 has 12 divisors (see below), whose sum is σ = 44984142084. Its totient is φ = 8568408000.

The previous prime is 21421019993. The next prime is 21421020041. The reversal of 21421020020 is 2002012412.

It can be written as a sum of positive squares in 2 ways, for example, as 3918259216 + 17502760804 = 62596^2 + 132298^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21421019977 and 21421020004.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 535525481 + ... + 535525520.

It is an arithmetic number, because the mean of its divisors is an integer number (3748678507).

Almost surely, 2^21421020020 is an apocalyptic number.

21421020020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21421020020 is an abundant number, since it is smaller than the sum of its proper divisors (23563122064).

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

21421020020 is a wasteful number, since it uses less digits than its factorization.

21421020020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1071051010 (or 1071051008 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 14.

Adding to 21421020020 its reverse (2002012412), we get a palindrome (23423032432).

The spelling of 21421020020 in words is "twenty-one billion, four hundred twenty-one million, twenty thousand, twenty".