21087966 has 16 divisors (see below), whose sum is σ = 42278544. Its totient is φ = 7012224.

The previous prime is 21087961. The next prime is 21087971. The reversal of 21087966 is 66978012.

It is an interprime number because it is at equal distance from previous prime (21087961) and next prime (21087971).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21087961) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1461 + ... + 6656.

It is an arithmetic number, because the mean of its divisors is an integer number (2642409).

Almost surely, 2^21087966 is an apocalyptic number.

21087966 is an abundant number, since it is smaller than the sum of its proper divisors (21190578).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21087966 is a wasteful number, since it uses less digits than its factorization.

21087966 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8555.

The product of its (nonzero) digits is 36288, while the sum is 39.

The square root of 21087966 is about 4592.1635423839. The cubic root of 21087966 is about 276.2771056441.

The spelling of 21087966 in words is "twenty-one million, eighty-seven thousand, nine hundred sixty-six".