21392905 has 8 divisors (see below), whose sum is σ = 25696512. Its totient is φ = 17097648.

The previous prime is 21392893. The next prime is 21392929. The reversal of 21392905 is 50929312.

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 21392905 - 2⁵ = 21392873 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7942 + ... + 10288.

It is an arithmetic number, because the mean of its divisors is an integer number (3212064).

Almost surely, 2^21392905 is an apocalyptic number.

It is an amenable number.

21392905 is a deficient number, since it is larger than the sum of its proper divisors (4303607).

21392905 is a wasteful number, since it uses less digits than its factorization.

21392905 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4175.

The product of its (nonzero) digits is 4860, while the sum is 31.

The square root of 21392905 is about 4625.2464799187. The cubic root of 21392905 is about 277.6024241124.

The spelling of 21392905 in words is "twenty-one million, three hundred ninety-two thousand, nine hundred five".