21369819 has 16 divisors (see below), whose sum is σ = 30044160. Its totient is φ = 13490880.

The previous prime is 21369811. The next prime is 21369847. The reversal of 21369819 is 91896312.

It is not a de Polignac number, because 21369819 - 2³ = 21369811 is a prime.

It is a super-2 number, since 2×21369819² = 913338328185522, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21369811) 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 15 ways as a sum of consecutive naturals, for example, 1927 + ... + 6815.

It is an arithmetic number, because the mean of its divisors is an integer number (1877760).

Almost surely, 2^21369819 is an apocalyptic number.

21369819 is a deficient number, since it is larger than the sum of its proper divisors (8674341).

21369819 is a wasteful number, since it uses less digits than its factorization.

21369819 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4970.

The product of its digits is 23328, while the sum is 39.

The square root of 21369819 is about 4622.7501554810. The cubic root of 21369819 is about 277.5025306157.

The spelling of 21369819 in words is "twenty-one million, three hundred sixty-nine thousand, eight hundred nineteen".