21046687 has 4 divisors (see below), whose sum is σ = 21061656. Its totient is φ = 21031720.

The previous prime is 21046681. The next prime is 21046709. The reversal of 21046687 is 78664012.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21046687 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 (21046681) 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, 5128 + ... + 8269.

It is an arithmetic number, because the mean of its divisors is an integer number (5265414).

Almost surely, 2^21046687 is an apocalyptic number.

21046687 is a deficient number, since it is larger than the sum of its proper divisors (14969).

21046687 is a wasteful number, since it uses less digits than its factorization.

21046687 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14968.

The product of its (nonzero) digits is 16128, while the sum is 34.

The square root of 21046687 is about 4587.6668362033. Note that the first 3 decimals coincide. The cubic root of 21046687 is about 276.0967201102.

The spelling of 21046687 in words is "twenty-one million, forty-six thousand, six hundred eighty-seven".