31000001221 has 4 divisors (see below), whose sum is σ = 35428572832. Its totient is φ = 26571429612.

The previous prime is 31000001213. The next prime is 31000001237. The reversal of 31000001221 is 12210000013.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 31000001221 - 2³ = 31000001213 is a prime.

It is a super-2 number, since 2×31000001221² (a number of 22 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 = 31000001198 and 31000001207.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31000001621) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2214285795 + ... + 2214285808.

It is an arithmetic number, because the mean of its divisors is an integer number (8857143208).

Almost surely, 2^31000001221 is an apocalyptic number.

It is an amenable number.

31000001221 is a deficient number, since it is larger than the sum of its proper divisors (4428571611).

31000001221 is an equidigital number, since it uses as much as digits as its factorization.

31000001221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4428571610.

The product of its (nonzero) digits is 12, while the sum is 10.

Adding to 31000001221 its reverse (12210000013), we get a palindrome (43210001234).

The spelling of 31000001221 in words is "thirty-one billion, one thousand, two hundred twenty-one".