21931706 has 4 divisors (see below), whose sum is σ = 32897562. Its totient is φ = 10965852.

The previous prime is 21931703. The next prime is 21931709. The reversal of 21931706 is 60713912.

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

It is an interprime number because it is at equal distance from previous prime (21931703) and next prime (21931709).

It can be written as a sum of positive squares in only one way, i.e., 20620681 + 1311025 = 4541^2 + 1145^2 .

It is not an unprimeable number, because it can be changed into a prime (21931703) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5482925 + ... + 5482928.

Almost surely, 2^21931706 is an apocalyptic number.

21931706 is a deficient number, since it is larger than the sum of its proper divisors (10965856).

21931706 is a wasteful number, since it uses less digits than its factorization.

21931706 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10965855.

The product of its (nonzero) digits is 2268, while the sum is 29.

The square root of 21931706 is about 4683.1299362713. The cubic root of 21931706 is about 279.9136893837.

The spelling of 21931706 in words is "twenty-one million, nine hundred thirty-one thousand, seven hundred six".