21997706 has 16 divisors (see below), whose sum is σ = 36244800. Its totient is φ = 9966528.

The previous prime is 21997697. The next prime is 21997709. The reversal of 21997706 is 60779912.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (21997709) 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, 11711 + ... + 13458.

It is an arithmetic number, because the mean of its divisors is an integer number (2265300).

Almost surely, 2^21997706 is an apocalyptic number.

21997706 is a deficient number, since it is larger than the sum of its proper divisors (14247094).

21997706 is a wasteful number, since it uses less digits than its factorization.

21997706 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25213.

The product of its (nonzero) digits is 47628, while the sum is 41.

The square root of 21997706 is about 4690.1712122267. The cubic root of 21997706 is about 280.1941935176.

The spelling of 21997706 in words is "twenty-one million, nine hundred ninety-seven thousand, seven hundred six".