21994917 has 16 divisors (see below), whose sum is σ = 33922560. Its totient is φ = 12416112.

The previous prime is 21994897. The next prime is 21994981. The reversal of 21994917 is 71949912.

It is not a de Polignac number, because 21994917 - 2¹⁰ = 21993893 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21995917) 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, 4567 + ... + 8052.

It is an arithmetic number, because the mean of its divisors is an integer number (2120160).

Almost surely, 2^21994917 is an apocalyptic number.

It is an amenable number.

21994917 is a deficient number, since it is larger than the sum of its proper divisors (11927643).

21994917 is a wasteful number, since it uses less digits than its factorization.

21994917 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12712.

The product of its digits is 40824, while the sum is 42.

The square root of 21994917 is about 4689.8738789012. The cubic root of 21994917 is about 280.1823514550.

The spelling of 21994917 in words is "twenty-one million, nine hundred ninety-four thousand, nine hundred seventeen".