21053439 has 20 divisors (see below), whose sum is σ = 34310760. Its totient is φ = 12759120.

The previous prime is 21053437. The next prime is 21053467. The reversal of 21053439 is 93435012.

It is not a de Polignac number, because 21053439 - 2¹ = 21053437 is a prime.

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21053437) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 10924 + ... + 12705.

It is an arithmetic number, because the mean of its divisors is an integer number (1715538).

Almost surely, 2^21053439 is an apocalyptic number.

21053439 is a deficient number, since it is larger than the sum of its proper divisors (13257321).

21053439 is a wasteful number, since it uses less digits than its factorization.

21053439 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23652 (or 23643 counting only the distinct ones).

The product of its (nonzero) digits is 3240, while the sum is 27.

The square root of 21053439 is about 4588.4026632370. The cubic root of 21053439 is about 276.1262418703.

The spelling of 21053439 in words is "twenty-one million, fifty-three thousand, four hundred thirty-nine".