21201201021 has 64 divisors (see below), whose sum is σ = 38980601856. Its totient is φ = 9891590400.

The previous prime is 21201200987. The next prime is 21201201061. The reversal of 21201201021 is 12010210212.

It is not a de Polignac number, because 21201201021 - 2⁹ = 21201200509 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21201200988 and 21201201006.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21201201061) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 15706 + ... + 206516.

It is an arithmetic number, because the mean of its divisors is an integer number (609071904).

Almost surely, 2^21201201021 is an apocalyptic number.

21201201021 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21201201021 is a deficient number, since it is larger than the sum of its proper divisors (17779400835).

21201201021 is a wasteful number, since it uses less digits than its factorization.

21201201021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 190882.

The product of its (nonzero) digits is 16, while the sum is 12.

Adding to 21201201021 its reverse (12010210212), we get a palindrome (33211411233).

It can be divided in two parts, 21201 and 201021, that added together give a palindrome (222222).

The spelling of 21201201021 in words is "twenty-one billion, two hundred one million, two hundred one thousand, twenty-one".