21020121010 has 128 divisors (see below), whose sum is σ = 44727427584. Its totient is φ = 6965145600.

The previous prime is 21020121007. The next prime is 21020121029. The reversal of 21020121010 is 1012102012.

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

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 66309372 + ... + 66309688.

It is an arithmetic number, because the mean of its divisors is an integer number (349433028).

Almost surely, 2^21020121010 is an apocalyptic number.

21020121010 is an abundant number, since it is smaller than the sum of its proper divisors (23707306574).

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

21020121010 is a wasteful number, since it uses less digits than its factorization.

21020121010 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 628.

The product of its (nonzero) digits is 8, while the sum is 10.

Adding to 21020121010 its reverse (1012102012), we get a palindrome (22032223022).

The spelling of 21020121010 in words is "twenty-one billion, twenty million, one hundred twenty-one thousand, ten".