21939707 has 4 divisors (see below), whose sum is σ = 23230296. Its totient is φ = 20649120.

The previous prime is 21939703. The next prime is 21939713. The reversal of 21939707 is 70793912.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21939707 - 2² = 21939703 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21939703) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 645269 + ... + 645302.

It is an arithmetic number, because the mean of its divisors is an integer number (5807574).

Almost surely, 2^21939707 is an apocalyptic number.

21939707 is a deficient number, since it is larger than the sum of its proper divisors (1290589).

21939707 is a wasteful number, since it uses less digits than its factorization.

21939707 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1290588.

The product of its (nonzero) digits is 23814, while the sum is 38.

The square root of 21939707 is about 4683.9840947638. The cubic root of 21939707 is about 279.9477240842.

The spelling of 21939707 in words is "twenty-one million, nine hundred thirty-nine thousand, seven hundred seven".