21662387 has 2 divisors, whose sum is σ = 21662388. Its totient is φ = 21662386.

The previous prime is 21662363. The next prime is 21662393. The reversal of 21662387 is 78326612.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21662387 - 2⁶ = 21662323 is a prime.

It is not a weakly prime, because it can be changed into another prime (21662327) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10831193 + 10831194.

It is an arithmetic number, because the mean of its divisors is an integer number (10831194).

Almost surely, 2^21662387 is an apocalyptic number.

21662387 is a deficient number, since it is larger than the sum of its proper divisors (1).

21662387 is an equidigital number, since it uses as much as digits as its factorization.

21662387 is an evil number, because the sum of its binary digits is even.

The product of its digits is 24192, while the sum is 35.

The square root of 21662387 is about 4654.2869486099. The cubic root of 21662387 is about 278.7631971069.

Adding to 21662387 its reverse (78326612), we get a palindrome (99988999).

The spelling of 21662387 in words is "twenty-one million, six hundred sixty-two thousand, three hundred eighty-seven".