21613240720993 has 2 divisors, whose sum is σ = 21613240720994. Its totient is φ = 21613240720992.

The previous prime is 21613240720979. The next prime is 21613240721047. The reversal of 21613240720993 is 39902704231612.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11847721970704 + 9765518750289 = 3442052^2 + 3124983^2 .

It is a cyclic number.

It is not a de Polignac number, because 21613240720993 - 2¹⁷ = 21613240589921 is a prime.

It is not a weakly prime, because it can be changed into another prime (21613240720933) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10806620360496 + 10806620360497.

It is an arithmetic number, because the mean of its divisors is an integer number (10806620360497).

Almost surely, 2^{21613240720993} is an apocalyptic number.

It is an amenable number.

21613240720993 is a deficient number, since it is larger than the sum of its proper divisors (1).

21613240720993 is an equidigital number, since it uses as much as digits as its factorization.

21613240720993 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 979776, while the sum is 49.

The spelling of 21613240720993 in words is "twenty-one trillion, six hundred thirteen billion, two hundred forty million, seven hundred twenty thousand, nine hundred ninety-three".