21195687 has 4 divisors (see below), whose sum is σ = 28260920. Its totient is φ = 14130456.

The previous prime is 21195679. The next prime is 21195739. The reversal of 21195687 is 78659112.

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

It is not a de Polignac number, because 21195687 - 2³ = 21195679 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 (21195667) 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, 3532612 + ... + 3532617.

It is an arithmetic number, because the mean of its divisors is an integer number (7065230).

Almost surely, 2^21195687 is an apocalyptic number.

21195687 is a deficient number, since it is larger than the sum of its proper divisors (7065233).

21195687 is an equidigital number, since it uses as much as digits as its factorization.

21195687 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7065232.

The product of its digits is 30240, while the sum is 39.

The square root of 21195687 is about 4603.8773875941. The cubic root of 21195687 is about 276.7467307515.

The spelling of 21195687 in words is "twenty-one million, one hundred ninety-five thousand, six hundred eighty-seven".