21396287 has 8 divisors (see below), whose sum is σ = 24146640. Its totient is φ = 18780160.

The previous prime is 21396269. The next prime is 21396289. The reversal of 21396287 is 78269312.

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 21396287 - 2⁸ = 21396031 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21396287.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21396289) 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, 33218 + ... + 33855.

It is an arithmetic number, because the mean of its divisors is an integer number (3018330).

Almost surely, 2^21396287 is an apocalyptic number.

21396287 is a deficient number, since it is larger than the sum of its proper divisors (2750353).

21396287 is a wasteful number, since it uses less digits than its factorization.

21396287 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 67113.

The product of its digits is 36288, while the sum is 38.

The square root of 21396287 is about 4625.6120676079. The cubic root of 21396287 is about 277.6170520452.

The spelling of 21396287 in words is "twenty-one million, three hundred ninety-six thousand, two hundred eighty-seven".