21917906 has 8 divisors (see below), whose sum is σ = 34607280. Its totient is φ = 10382148.

The previous prime is 21917891. The next prime is 21917921. The reversal of 21917906 is 60971912.

It is an interprime number because it is at equal distance from previous prime (21917891) and next prime (21917921).

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

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 288356 + ... + 288431.

It is an arithmetic number, because the mean of its divisors is an integer number (4325910).

Almost surely, 2^21917906 is an apocalyptic number.

21917906 is a deficient number, since it is larger than the sum of its proper divisors (12689374).

21917906 is a wasteful number, since it uses less digits than its factorization.

21917906 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 576808.

The product of its (nonzero) digits is 6804, while the sum is 35.

The square root of 21917906 is about 4681.6563308299. The cubic root of 21917906 is about 279.8549674069.

The spelling of 21917906 in words is "twenty-one million, nine hundred seventeen thousand, nine hundred six".