21368387 has 2 divisors, whose sum is σ = 21368388. Its totient is φ = 21368386.

The previous prime is 21368363. The next prime is 21368401. The reversal of 21368387 is 78386312.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21368387 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21368387.

It is not a weakly prime, because it can be changed into another prime (21368287) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10684193 + 10684194.

It is an arithmetic number, because the mean of its divisors is an integer number (10684194).

Almost surely, 2^21368387 is an apocalyptic number.

21368387 is a deficient number, since it is larger than the sum of its proper divisors (1).

21368387 is an equidigital number, since it uses as much as digits as its factorization.

21368387 is an evil number, because the sum of its binary digits is even.

The product of its digits is 48384, while the sum is 38.

The square root of 21368387 is about 4622.5952667306. The cubic root of 21368387 is about 277.4963319592.

The spelling of 21368387 in words is "twenty-one million, three hundred sixty-eight thousand, three hundred eighty-seven".