21121320031 has 4 divisors (see below), whose sum is σ = 24138651472. Its totient is φ = 18103988592.

The previous prime is 21121320001. The next prime is 21121320071. The reversal of 21121320031 is 13002312112.

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 21121320031 - 2⁷ = 21121319903 is a prime.

It is a super-2 number, since 2×21121320031² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21121319987 and 21121320014.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21121320001) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1508665710 + ... + 1508665723.

It is an arithmetic number, because the mean of its divisors is an integer number (6034662868).

Almost surely, 2^21121320031 is an apocalyptic number.

21121320031 is a deficient number, since it is larger than the sum of its proper divisors (3017331441).

21121320031 is an equidigital number, since it uses as much as digits as its factorization.

21121320031 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3017331440.

The product of its (nonzero) digits is 72, while the sum is 16.

Adding to 21121320031 its reverse (13002312112), we get a palindrome (34123632143).

The spelling of 21121320031 in words is "twenty-one billion, one hundred twenty-one million, three hundred twenty thousand, thirty-one".