21240929393 has 2 divisors, whose sum is σ = 21240929394. Its totient is φ = 21240929392.

The previous prime is 21240929351. The next prime is 21240929419. The reversal of 21240929393 is 39392904212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14286703729 + 6954225664 = 119527^2 + 83392^2 .

It is a cyclic number.

It is not a de Polignac number, because 21240929393 - 2²⁴ = 21224152177 is a prime.

It is a super-2 number, since 2×21240929393² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21240929093) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10620464696 + 10620464697.

It is an arithmetic number, because the mean of its divisors is an integer number (10620464697).

Almost surely, 2^21240929393 is an apocalyptic number.

It is an amenable number.

21240929393 is a deficient number, since it is larger than the sum of its proper divisors (1).

21240929393 is an equidigital number, since it uses as much as digits as its factorization.

21240929393 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 209952, while the sum is 44.

The spelling of 21240929393 in words is "twenty-one billion, two hundred forty million, nine hundred twenty-nine thousand, three hundred ninety-three".