21152521213 has 4 divisors (see below), whose sum is σ = 21370588540. Its totient is φ = 20934453888.

The previous prime is 21152521211. The next prime is 21152521219. The reversal of 21152521213 is 31212525112.

It is a happy number.

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 6507164889 + 14645356324 = 80667^2 + 121018^2 .

It is a cyclic number.

It is not a de Polignac number, because 21152521213 - 2¹ = 21152521211 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 (21152521211) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 109033518 + ... + 109033711.

It is an arithmetic number, because the mean of its divisors is an integer number (5342647135).

Almost surely, 2^21152521213 is an apocalyptic number.

It is an amenable number.

21152521213 is a deficient number, since it is larger than the sum of its proper divisors (218067327).

21152521213 is an equidigital number, since it uses as much as digits as its factorization.

21152521213 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 218067326.

The product of its digits is 1200, while the sum is 25.

The spelling of 21152521213 in words is "twenty-one billion, one hundred fifty-two million, five hundred twenty-one thousand, two hundred thirteen".