21305640231 has 24 divisors (see below), whose sum is σ = 31115644560. Its totient is φ = 14046909696.

The previous prime is 21305640211. The next prime is 21305640241. The reversal of 21305640231 is 13204650312.

21305640231 is a `hidden beast` number, since 2 + 13 + 0 + 5 + 640 + 2 + 3 + 1 = 666.

It is not a de Polignac number, because 21305640231 - 2⁵ = 21305640199 is a prime.

It is a super-2 number, since 2×21305640231² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21305640195 and 21305640204.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21305640211) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 552405 + ... + 589713.

It is an arithmetic number, because the mean of its divisors is an integer number (1296485190).

Almost surely, 2^21305640231 is an apocalyptic number.

21305640231 is a deficient number, since it is larger than the sum of its proper divisors (9810004329).

21305640231 is a wasteful number, since it uses less digits than its factorization.

21305640231 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 38015 (or 38012 counting only the distinct ones).

The product of its (nonzero) digits is 4320, while the sum is 27.

The spelling of 21305640231 in words is "twenty-one billion, three hundred five million, six hundred forty thousand, two hundred thirty-one".