21358931091 has 4 divisors (see below), whose sum is σ = 28478574792. Its totient is φ = 14239287392.

The previous prime is 21358931051. The next prime is 21358931129. The reversal of 21358931091 is 19013985312.

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 21358931091 - 2¹¹ = 21358929043 is a prime.

It is a super-3 number, since 3×21358931091³ (a number of 32 digits) contains 333 as substring.

It is not an unprimeable number, because it can be changed into a prime (21358931051) 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, 3559821846 + ... + 3559821851.

It is an arithmetic number, because the mean of its divisors is an integer number (7119643698).

Almost surely, 2^21358931091 is an apocalyptic number.

21358931091 is a deficient number, since it is larger than the sum of its proper divisors (7119643701).

21358931091 is an equidigital number, since it uses as much as digits as its factorization.

21358931091 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7119643700.

The product of its (nonzero) digits is 58320, while the sum is 42.

The spelling of 21358931091 in words is "twenty-one billion, three hundred fifty-eight million, nine hundred thirty-one thousand, ninety-one".