21492439609 has 3 divisors (see below), whose sum is σ = 21492586213. Its totient is φ = 21492293006.

The previous prime is 21492439571. The next prime is 21492439621. The reversal of 21492439609 is 90693429412.

It is a happy number.

The square root of 21492439609 is 146603.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is not a de Polignac number, because 21492439609 - 2²¹ = 21490342457 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21492439649) 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 in 2 ways as a sum of consecutive naturals, for example, 73302 + ... + 219904.

Almost surely, 2^21492439609 is an apocalyptic number.

21492439609 is the 146603-rd square number.

21492439609 is the 73302-nd centered octagonal number.

It is an amenable number.

21492439609 is a deficient number, since it is larger than the sum of its proper divisors (146604).

21492439609 is an frugal number, since it uses more digits than its factorization.

21492439609 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 293206 (or 146603 counting only the distinct ones).

The product of its (nonzero) digits is 839808, while the sum is 49.

Multiplying 21492439609 by its sum of digits (49), we get a square (1053129540841 = 1026221²).

The spelling of 21492439609 in words is "twenty-one billion, four hundred ninety-two million, four hundred thirty-nine thousand, six hundred nine".