21251103493 has 2 divisors, whose sum is σ = 21251103494. Its totient is φ = 21251103492.

The previous prime is 21251103481. The next prime is 21251103547. The reversal of 21251103493 is 39430115212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12471975684 + 8779127809 = 111678^2 + 93697^2 .

It is a cyclic number.

It is not a de Polignac number, because 21251103493 - 2¹³ = 21251095301 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21251103403) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10625551746 + 10625551747.

It is an arithmetic number, because the mean of its divisors is an integer number (10625551747).

Almost surely, 2^21251103493 is an apocalyptic number.

It is an amenable number.

21251103493 is a deficient number, since it is larger than the sum of its proper divisors (1).

21251103493 is an equidigital number, since it uses as much as digits as its factorization.

21251103493 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 6480, while the sum is 31.

The spelling of 21251103493 in words is "twenty-one billion, two hundred fifty-one million, one hundred three thousand, four hundred ninety-three".