21621240313 has 2 divisors, whose sum is σ = 21621240314. Its totient is φ = 21621240312.

The previous prime is 21621240307. The next prime is 21621240317. The reversal of 21621240313 is 31304212612.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19532019049 + 2089221264 = 139757^2 + 45708^2 .

It is a cyclic number.

It is not a de Polignac number, because 21621240313 - 2²⁵ = 21587685881 is a prime.

It is not a weakly prime, because it can be changed into another prime (21621240317) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10810620156 + 10810620157.

It is an arithmetic number, because the mean of its divisors is an integer number (10810620157).

Almost surely, 2^21621240313 is an apocalyptic number.

It is an amenable number.

21621240313 is a deficient number, since it is larger than the sum of its proper divisors (1).

21621240313 is an equidigital number, since it uses as much as digits as its factorization.

21621240313 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1728, while the sum is 25.

Adding to 21621240313 its reverse (31304212612), we get a palindrome (52925452925).

The spelling of 21621240313 in words is "twenty-one billion, six hundred twenty-one million, two hundred forty thousand, three hundred thirteen".