21394459709 has 4 divisors (see below), whose sum is σ = 24450811104. Its totient is φ = 18338108316.

The previous prime is 21394459687. The next prime is 21394459721. The reversal of 21394459709 is 90795449312.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21394459709 - 2⁸ = 21394459453 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21394459729) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1528175687 + ... + 1528175700.

It is an arithmetic number, because the mean of its divisors is an integer number (6112702776).

Almost surely, 2^21394459709 is an apocalyptic number.

It is an amenable number.

21394459709 is a deficient number, since it is larger than the sum of its proper divisors (3056351395).

21394459709 is an equidigital number, since it uses as much as digits as its factorization.

21394459709 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3056351394.

The product of its (nonzero) digits is 2449440, while the sum is 53.

The spelling of 21394459709 in words is "twenty-one billion, three hundred ninety-four million, four hundred fifty-nine thousand, seven hundred nine".