21431236389 has 16 divisors (see below), whose sum is σ = 28628728128. Its totient is φ = 14260644992.

The previous prime is 21431236373. The next prime is 21431236397. The reversal of 21431236389 is 98363213412.

It is a cyclic number.

It is not a de Polignac number, because 21431236389 - 2⁴ = 21431236373 is a prime.

It is a super-4 number, since 4×21431236389⁴ (a number of 42 digits) contains 4444 as substring. Note that it is a super-d number also for d = 2.

It is a self number, because there is not a number n which added to its sum of digits gives 21431236389.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21431236319) 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, 5826619 + ... + 5830295.

It is an arithmetic number, because the mean of its divisors is an integer number (1789295508).

Almost surely, 2^21431236389 is an apocalyptic number.

It is an amenable number.

21431236389 is a deficient number, since it is larger than the sum of its proper divisors (7197491739).

21431236389 is a wasteful number, since it uses less digits than its factorization.

21431236389 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6804.

The product of its digits is 186624, while the sum is 42.

The spelling of 21431236389 in words is "twenty-one billion, four hundred thirty-one million, two hundred thirty-six thousand, three hundred eighty-nine".