21343609 has 16 divisors (see below), whose sum is σ = 26053632. Its totient is φ = 17086608.

The previous prime is 21343607. The next prime is 21343613. The reversal of 21343609 is 90634312.

It is not a de Polignac number, because 21343609 - 2¹ = 21343607 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21343601) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5382 + ... + 8464.

It is an arithmetic number, because the mean of its divisors is an integer number (1628352).

Almost surely, 2^21343609 is an apocalyptic number.

It is an amenable number.

21343609 is a deficient number, since it is larger than the sum of its proper divisors (4710023).

21343609 is a wasteful number, since it uses less digits than its factorization.

21343609 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3156.

The product of its (nonzero) digits is 3888, while the sum is 28.

The square root of 21343609 is about 4619.9143931463. The cubic root of 21343609 is about 277.3890322759.

It can be divided in two parts, 21343 and 609, that added together give a cube (21952 = 28³).

The spelling of 21343609 in words is "twenty-one million, three hundred forty-three thousand, six hundred nine".