21068387 has 4 divisors (see below), whose sum is σ = 21085680. Its totient is φ = 21051096.

The previous prime is 21068357. The next prime is 21068417. The reversal of 21068387 is 78386012.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (21068357) and next prime (21068417).

It is a cyclic number.

It is not a de Polignac number, because 21068387 - 2¹² = 21064291 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21068317) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6668 + ... + 9305.

It is an arithmetic number, because the mean of its divisors is an integer number (5271420).

Almost surely, 2^21068387 is an apocalyptic number.

21068387 is a deficient number, since it is larger than the sum of its proper divisors (17293).

21068387 is a wasteful number, since it uses less digits than its factorization.

21068387 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17292.

The product of its (nonzero) digits is 16128, while the sum is 35.

The square root of 21068387 is about 4590.0312635101. The cubic root of 21068387 is about 276.1915765423.

The spelling of 21068387 in words is "twenty-one million, sixty-eight thousand, three hundred eighty-seven".