21394905 has 16 divisors (see below), whose sum is σ = 39122304. Its totient is φ = 9780480.

The previous prime is 21394903. The next prime is 21394921. The reversal of 21394905 is 50949312.

It is not a de Polignac number, because 21394905 - 2¹ = 21394903 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21394903) 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, 101776 + ... + 101985.

It is an arithmetic number, because the mean of its divisors is an integer number (2445144).

Almost surely, 2^21394905 is an apocalyptic number.

It is an amenable number.

21394905 is a deficient number, since it is larger than the sum of its proper divisors (17727399).

21394905 is a wasteful number, since it uses less digits than its factorization.

21394905 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 203776.

The product of its (nonzero) digits is 9720, while the sum is 33.

The square root of 21394905 is about 4625.4626795597. The cubic root of 21394905 is about 277.6110747616.

The spelling of 21394905 in words is "twenty-one million, three hundred ninety-four thousand, nine hundred five".