21700807 has 4 divisors (see below), whose sum is σ = 21846600. Its totient is φ = 21555016.

The previous prime is 21700771. The next prime is 21700829. The reversal of 21700807 is 70800712.

It is a happy number.

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 21700807 - 2¹¹ = 21698759 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21701807) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 72673 + ... + 72970.

It is an arithmetic number, because the mean of its divisors is an integer number (5461650).

Almost surely, 2^21700807 is an apocalyptic number.

21700807 is a deficient number, since it is larger than the sum of its proper divisors (145793).

21700807 is a wasteful number, since it uses less digits than its factorization.

21700807 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 145792.

The product of its (nonzero) digits is 784, while the sum is 25.

The square root of 21700807 is about 4658.4124978366. The cubic root of 21700807 is about 278.9279028175.

The spelling of 21700807 in words is "twenty-one million, seven hundred thousand, eight hundred seven".