21196387 has 4 divisors (see below), whose sum is σ = 21234600. Its totient is φ = 21158176.

The previous prime is 21196349. The next prime is 21196397. The reversal of 21196387 is 78369112.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21196387 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21196327) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 18262 + ... + 19387.

It is an arithmetic number, because the mean of its divisors is an integer number (5308650).

Almost surely, 2^21196387 is an apocalyptic number.

21196387 is a deficient number, since it is larger than the sum of its proper divisors (38213).

21196387 is an equidigital number, since it uses as much as digits as its factorization.

21196387 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 38212.

The product of its digits is 18144, while the sum is 37.

The square root of 21196387 is about 4603.9534098425. The cubic root of 21196387 is about 276.7497772923.

The spelling of 21196387 in words is "twenty-one million, one hundred ninety-six thousand, three hundred eighty-seven".