21632287 has 2 divisors, whose sum is σ = 21632288. Its totient is φ = 21632286.

The previous prime is 21632257. The next prime is 21632323. The reversal of 21632287 is 78223612.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21632287 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21632257) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10816143 + 10816144.

It is an arithmetic number, because the mean of its divisors is an integer number (10816144).

Almost surely, 2^21632287 is an apocalyptic number.

21632287 is a deficient number, since it is larger than the sum of its proper divisors (1).

21632287 is an equidigital number, since it uses as much as digits as its factorization.

21632287 is an evil number, because the sum of its binary digits is even.

The product of its digits is 8064, while the sum is 31.

The square root of 21632287 is about 4651.0522465352. The cubic root of 21632287 is about 278.6340229524.

Adding to 21632287 its reverse (78223612), we get a palindrome (99855899).

The spelling of 21632287 in words is "twenty-one million, six hundred thirty-two thousand, two hundred eighty-seven".