21906705 has 8 divisors (see below), whose sum is σ = 35050752. Its totient is φ = 11683568.

The previous prime is 21906697. The next prime is 21906707. The reversal of 21906705 is 50760912.

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 21906705 - 2³ = 21906697 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21906707) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 730209 + ... + 730238.

It is an arithmetic number, because the mean of its divisors is an integer number (4381344).

Almost surely, 2^21906705 is an apocalyptic number.

It is an amenable number.

21906705 is a deficient number, since it is larger than the sum of its proper divisors (13144047).

21906705 is a wasteful number, since it uses less digits than its factorization.

21906705 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1460455.

The product of its (nonzero) digits is 3780, while the sum is 30.

The square root of 21906705 is about 4680.4599132991. The cubic root of 21906705 is about 279.8072866108.

The spelling of 21906705 in words is "twenty-one million, nine hundred six thousand, seven hundred five".