21105305213 has 8 divisors (see below), whose sum is σ = 21224111832. Its totient is φ = 20986616896.

The previous prime is 21105305189. The next prime is 21105305237. The reversal of 21105305213 is 31250350112.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21105305189) and next prime (21105305237).

It can be written as a sum of positive squares in 4 ways, for example, as 7513942489 + 13591362724 = 86683^2 + 116582^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21105305213 - 2²² = 21101110909 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 (21105305413) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 341231 + ... + 398307.

It is an arithmetic number, because the mean of its divisors is an integer number (2653013979).

Almost surely, 2^21105305213 is an apocalyptic number.

It is an amenable number.

21105305213 is a deficient number, since it is larger than the sum of its proper divisors (118806619).

21105305213 is a wasteful number, since it uses less digits than its factorization.

21105305213 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 59151.

The product of its (nonzero) digits is 900, while the sum is 23.

Adding to 21105305213 its reverse (31250350112), we get a palindrome (52355655325).

The spelling of 21105305213 in words is "twenty-one billion, one hundred five million, three hundred five thousand, two hundred thirteen".