21672287 has 8 divisors (see below), whose sum is σ = 26673696. Its totient is φ = 17147232.

The previous prime is 21672271. The next prime is 21672319. The reversal of 21672287 is 78227612.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21672287 - 2⁴ = 21672271 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21672227) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 118988 + ... + 119169.

It is an arithmetic number, because the mean of its divisors is an integer number (3334212).

Almost surely, 2^21672287 is an apocalyptic number.

21672287 is a deficient number, since it is larger than the sum of its proper divisors (5001409).

21672287 is a wasteful number, since it uses less digits than its factorization.

21672287 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 238177.

The product of its digits is 18816, while the sum is 35.

The square root of 21672287 is about 4655.3503627547. The cubic root of 21672287 is about 278.8056568066.

Adding to 21672287 its reverse (78227612), we get a palindrome (99899899).

The spelling of 21672287 in words is "twenty-one million, six hundred seventy-two thousand, two hundred eighty-seven".