21253813379 has 2 divisors, whose sum is σ = 21253813380. Its totient is φ = 21253813378.

The previous prime is 21253813363. The next prime is 21253813397. The reversal of 21253813379 is 97331835212.

Together with next prime (21253813397) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21253813379 - 2⁴ = 21253813363 is a prime.

It is not a weakly prime, because it can be changed into another prime (21253813349) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10626906689 + 10626906690.

It is an arithmetic number, because the mean of its divisors is an integer number (10626906690).

Almost surely, 2^21253813379 is an apocalyptic number.

21253813379 is a deficient number, since it is larger than the sum of its proper divisors (1).

21253813379 is an equidigital number, since it uses as much as digits as its factorization.

21253813379 is an evil number, because the sum of its binary digits is even.

The product of its digits is 272160, while the sum is 44.

The spelling of 21253813379 in words is "twenty-one billion, two hundred fifty-three million, eight hundred thirteen thousand, three hundred seventy-nine".