21215248993 has 2 divisors, whose sum is σ = 21215248994. Its totient is φ = 21215248992.

The previous prime is 21215248937. The next prime is 21215248997. The reversal of 21215248993 is 39984251212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 10764685009 + 10450563984 = 103753^2 + 102228^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21215248993 is a prime.

It is not a weakly prime, because it can be changed into another prime (21215248997) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10607624496 + 10607624497.

It is an arithmetic number, because the mean of its divisors is an integer number (10607624497).

Almost surely, 2^21215248993 is an apocalyptic number.

It is an amenable number.

21215248993 is a deficient number, since it is larger than the sum of its proper divisors (1).

21215248993 is an equidigital number, since it uses as much as digits as its factorization.

21215248993 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 311040, while the sum is 46.

The spelling of 21215248993 in words is "twenty-one billion, two hundred fifteen million, two hundred forty-eight thousand, nine hundred ninety-three".