21100020013 has 4 divisors (see below), whose sum is σ = 21827606940. Its totient is φ = 20372433088.

The previous prime is 21100020001. The next prime is 21100020023. The reversal of 21100020013 is 31002000112.

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 16497347364 + 4602672649 = 128442^2 + 67843^2 .

It is a cyclic number.

It is not a de Polignac number, because 21100020013 - 2³³ = 12510085421 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21100020023) 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, 363793420 + ... + 363793477.

It is an arithmetic number, because the mean of its divisors is an integer number (5456901735).

Almost surely, 2^21100020013 is an apocalyptic number.

It is an amenable number.

21100020013 is a deficient number, since it is larger than the sum of its proper divisors (727586927).

21100020013 is an equidigital number, since it uses as much as digits as its factorization.

21100020013 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 727586926.

The product of its (nonzero) digits is 12, while the sum is 10.

Adding to 21100020013 its reverse (31002000112), we get a palindrome (52102020125).

The spelling of 21100020013 in words is "twenty-one billion, one hundred million, twenty thousand, thirteen".