20101100021 has 4 divisors (see below), whose sum is σ = 20103652044. Its totient is φ = 20098548000.

The previous prime is 20101100017. The next prime is 20101100059. The reversal of 20101100021 is 12000110102.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 11565927025 + 8535172996 = 107545^2 + 92386^2 .

It is a cyclic number.

It is not a de Polignac number, because 20101100021 - 2² = 20101100017 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 20101099981 and 20101100008.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20101106021) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1264160 + ... + 1279961.

It is an arithmetic number, because the mean of its divisors is an integer number (5025913011).

Almost surely, 2^20101100021 is an apocalyptic number.

It is an amenable number.

20101100021 is a deficient number, since it is larger than the sum of its proper divisors (2552023).

20101100021 is an equidigital number, since it uses as much as digits as its factorization.

20101100021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2552022.

The product of its (nonzero) digits is 4, while the sum is 8.

Adding to 20101100021 its reverse (12000110102), we get a palindrome (32101210123).

The spelling of 20101100021 in words is "twenty billion, one hundred one million, one hundred thousand, twenty-one".