21297263 has 4 divisors (see below), whose sum is σ = 22935528. Its totient is φ = 19659000.

The previous prime is 21297259. The next prime is 21297293. The reversal of 21297263 is 36279212.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 21297263 - 2² = 21297259 is a prime.

It is a super-2 number, since 2×21297263² = 907146822582338, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21297203) 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, 819113 + ... + 819138.

It is an arithmetic number, because the mean of its divisors is an integer number (5733882).

Almost surely, 2^21297263 is an apocalyptic number.

21297263 is a deficient number, since it is larger than the sum of its proper divisors (1638265).

21297263 is a wasteful number, since it uses less digits than its factorization.

21297263 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1638264.

The product of its digits is 9072, while the sum is 32.

The square root of 21297263 is about 4614.8957734709. The cubic root of 21297263 is about 277.1881104839.

The spelling of 21297263 in words is "twenty-one million, two hundred ninety-seven thousand, two hundred sixty-three".