21426958391 has 4 divisors (see below), whose sum is σ = 21451787712. Its totient is φ = 21402129072.

The previous prime is 21426958387. The next prime is 21426958411. The reversal of 21426958391 is 19385962412.

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 21426958391 - 2² = 21426958387 is a prime.

It is a super-3 number, since 3×21426958391³ (a number of 32 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21426948391) 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 3 ways as a sum of consecutive naturals, for example, 12413366 + ... + 12415091.

It is an arithmetic number, because the mean of its divisors is an integer number (5362946928).

Almost surely, 2^21426958391 is an apocalyptic number.

21426958391 is a deficient number, since it is larger than the sum of its proper divisors (24829321).

21426958391 is an equidigital number, since it uses as much as digits as its factorization.

21426958391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24829320.

The product of its digits is 933120, while the sum is 50.

The spelling of 21426958391 in words is "twenty-one billion, four hundred twenty-six million, nine hundred fifty-eight thousand, three hundred ninety-one".