20913905 has 8 divisors (see below), whose sum is σ = 25224000. Its totient is φ = 16646256.

The previous prime is 20913887. The next prime is 20913931. The reversal of 20913905 is 50931902.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 20913905 - 2²⁴ = 4136689 is a prime.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9515 + ... + 11504.

It is an arithmetic number, because the mean of its divisors is an integer number (3153000).

Almost surely, 2^20913905 is an apocalyptic number.

It is an amenable number.

20913905 is a deficient number, since it is larger than the sum of its proper divisors (4310095).

20913905 is a wasteful number, since it uses less digits than its factorization.

20913905 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21223.

The product of its (nonzero) digits is 2430, while the sum is 29.

The square root of 20913905 is about 4573.1723125201. The cubic root of 20913905 is about 275.5148701409.

The spelling of 20913905 in words is "twenty million, nine hundred thirteen thousand, nine hundred five".