21243001439 has 16 divisors (see below), whose sum is σ = 23979179520. Its totient is φ = 18641316960.

The previous prime is 21243001369. The next prime is 21243001453. The reversal of 21243001439 is 93410034212.

It is a cyclic number.

It is not a de Polignac number, because 21243001439 - 2⁸ = 21243001183 is a prime.

It is a super-2 number, since 2×21243001439² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (29).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21243007439) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2447822 + ... + 2456484.

It is an arithmetic number, because the mean of its divisors is an integer number (1498698720).

Almost surely, 2^21243001439 is an apocalyptic number.

21243001439 is a gapful number since it is divisible by the number (29) formed by its first and last digit.

21243001439 is a deficient number, since it is larger than the sum of its proper divisors (2736178081).

21243001439 is a wasteful number, since it uses less digits than its factorization.

21243001439 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16390.

The product of its (nonzero) digits is 5184, while the sum is 29.

The spelling of 21243001439 in words is "twenty-one billion, two hundred forty-three million, one thousand, four hundred thirty-nine".