21707506 has 4 divisors (see below), whose sum is σ = 32561262. Its totient is φ = 10853752.

The previous prime is 21707501. The next prime is 21707507. The reversal of 21707506 is 60570712.

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

It can be written as a sum of positive squares in only one way, i.e., 21706281 + 1225 = 4659^2 + 35^2 .

It is not an unprimeable number, because it can be changed into a prime (21707501) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5426875 + ... + 5426878.

Almost surely, 2^21707506 is an apocalyptic number.

21707506 is a deficient number, since it is larger than the sum of its proper divisors (10853756).

21707506 is a wasteful number, since it uses less digits than its factorization.

21707506 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10853755.

The product of its (nonzero) digits is 2940, while the sum is 28.

The square root of 21707506 is about 4659.1314641250. The cubic root of 21707506 is about 278.9566013782.

The spelling of 21707506 in words is "twenty-one million, seven hundred seven thousand, five hundred six".