21288297 has 4 divisors (see below), whose sum is σ = 28384400. Its totient is φ = 14192196.

The previous prime is 21288259. The next prime is 21288343. The reversal of 21288297 is 79288212.

21288297 = 1079² + 1080² + ... + 1096².

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 21288297 - 2¹¹ = 21286249 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21288217) 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, 3548047 + ... + 3548052.

It is an arithmetic number, because the mean of its divisors is an integer number (7096100).

Almost surely, 2^21288297 is an apocalyptic number.

It is an amenable number.

21288297 is a deficient number, since it is larger than the sum of its proper divisors (7096103).

21288297 is an equidigital number, since it uses as much as digits as its factorization.

21288297 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7096102.

The product of its digits is 32256, while the sum is 39.

The square root of 21288297 is about 4613.9242516539. The cubic root of 21288297 is about 277.1492069334.

The spelling of 21288297 in words is "twenty-one million, two hundred eighty-eight thousand, two hundred ninety-seven".