21087297 has 96 divisors (see below), whose sum is σ = 41932800. Its totient is φ = 10478160.

The previous prime is 21087289. The next prime is 21087331. The reversal of 21087297 is 79278012.

It is not a de Polignac number, because 21087297 - 2³ = 21087289 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21087277) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 916828 + ... + 916850.

It is an arithmetic number, because the mean of its divisors is an integer number (436800).

Almost surely, 2^21087297 is an apocalyptic number.

21087297 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

It is an amenable number.

21087297 is a deficient number, since it is larger than the sum of its proper divisors (20845503).

21087297 is an equidigital number, since it uses as much as digits as its factorization.

21087297 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 70 (or 44 counting only the distinct ones).

The product of its (nonzero) digits is 14112, while the sum is 36.

The square root of 21087297 is about 4592.0907003238. The cubic root of 21087297 is about 276.2741840515.

The spelling of 21087297 in words is "twenty-one million, eighty-seven thousand, two hundred ninety-seven".