21000331613 has 2 divisors, whose sum is σ = 21000331614. Its totient is φ = 21000331612.

The previous prime is 21000331589. The next prime is 21000331619. The reversal of 21000331613 is 31613300012.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19948172644 + 1052158969 = 141238^2 + 32437^2 .

It is a cyclic number.

It is not a de Polignac number, because 21000331613 - 2⁶ = 21000331549 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21000331619) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10500165806 + 10500165807.

It is an arithmetic number, because the mean of its divisors is an integer number (10500165807).

Almost surely, 2^21000331613 is an apocalyptic number.

It is an amenable number.

21000331613 is a deficient number, since it is larger than the sum of its proper divisors (1).

21000331613 is an equidigital number, since it uses as much as digits as its factorization.

21000331613 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 324, while the sum is 20.

Adding to 21000331613 its reverse (31613300012), we get a palindrome (52613631625).

The spelling of 21000331613 in words is "twenty-one billion, three hundred thirty-one thousand, six hundred thirteen".