21392109 has 12 divisors (see below), whose sum is σ = 30940000. Its totient is φ = 14242824.

The previous prime is 21392099. The next prime is 21392117. The reversal of 21392109 is 90129312.

It is not a de Polignac number, because 21392109 - 2¹² = 21388013 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21392149) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 11742 + ... + 13440.

Almost surely, 2^21392109 is an apocalyptic number.

It is an amenable number.

21392109 is a deficient number, since it is larger than the sum of its proper divisors (9547891).

21392109 is a wasteful number, since it uses less digits than its factorization.

21392109 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3104 (or 3101 counting only the distinct ones).

The product of its (nonzero) digits is 972, while the sum is 27.

The square root of 21392109 is about 4625.1604296500. The cubic root of 21392109 is about 277.5989810040.

The spelling of 21392109 in words is "twenty-one million, three hundred ninety-two thousand, one hundred nine".