21253442879 has 2 divisors, whose sum is σ = 21253442880. Its totient is φ = 21253442878.

The previous prime is 21253442863. The next prime is 21253442927. The reversal of 21253442879 is 97824435212.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21253442879 - 2⁴ = 21253442863 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21253442809) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10626721439 + 10626721440.

It is an arithmetic number, because the mean of its divisors is an integer number (10626721440).

Almost surely, 2^21253442879 is an apocalyptic number.

21253442879 is a deficient number, since it is larger than the sum of its proper divisors (1).

21253442879 is an equidigital number, since it uses as much as digits as its factorization.

21253442879 is an evil number, because the sum of its binary digits is even.

The product of its digits is 967680, while the sum is 47.

The spelling of 21253442879 in words is "twenty-one billion, two hundred fifty-three million, four hundred forty-two thousand, eight hundred seventy-nine".