21387011 has 4 divisors (see below), whose sum is σ = 21523392. Its totient is φ = 21250632.

The previous prime is 21387001. The next prime is 21387059. The reversal of 21387011 is 11078312.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 21387011 - 2⁶ = 21386947 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21387001) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 67955 + ... + 68268.

It is an arithmetic number, because the mean of its divisors is an integer number (5380848).

Almost surely, 2^21387011 is an apocalyptic number.

21387011 is a deficient number, since it is larger than the sum of its proper divisors (136381).

21387011 is a wasteful number, since it uses less digits than its factorization.

21387011 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 136380.

The product of its (nonzero) digits is 336, while the sum is 23.

The square root of 21387011 is about 4624.6092807934. The cubic root of 21387011 is about 277.5769275132.

The spelling of 21387011 in words is "twenty-one million, three hundred eighty-seven thousand, eleven".