21566159431 has 4 divisors (see below), whose sum is σ = 21779685864. Its totient is φ = 21352633000.

The previous prime is 21566159429. The next prime is 21566159521. The reversal of 21566159431 is 13495166512.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21566159431 - 2¹ = 21566159429 is a prime.

It is a super-2 number, since 2×21566159431² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21566159411) 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 3 ways as a sum of consecutive naturals, for example, 106763065 + ... + 106763266.

It is an arithmetic number, because the mean of its divisors is an integer number (5444921466).

Almost surely, 2^21566159431 is an apocalyptic number.

21566159431 is a deficient number, since it is larger than the sum of its proper divisors (213526433).

21566159431 is a wasteful number, since it uses less digits than its factorization.

21566159431 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 213526432.

The product of its digits is 194400, while the sum is 43.

The spelling of 21566159431 in words is "twenty-one billion, five hundred sixty-six million, one hundred fifty-nine thousand, four hundred thirty-one".