31221011 has 4 divisors (see below), whose sum is σ = 31302912. Its totient is φ = 31139112.

The previous prime is 31220989. The next prime is 31221017. The reversal of 31221011 is 11012213.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-31221011 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 31220983 and 31221001.

It is not an unprimeable number, because it can be changed into a prime (31221017) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 40376 + ... + 41141.

It is an arithmetic number, because the mean of its divisors is an integer number (7825728).

Almost surely, 2^31221011 is an apocalyptic number.

31221011 is a deficient number, since it is larger than the sum of its proper divisors (81901).

31221011 is an equidigital number, since it uses as much as digits as its factorization.

31221011 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 81900.

The product of its (nonzero) digits is 12, while the sum is 11.

The square root of 31221011 is about 5587.5764871722. The cubic root of 31221011 is about 314.8828354047.

Adding to 31221011 its reverse (11012213), we get a palindrome (42233224).

The spelling of 31221011 in words is "thirty-one million, two hundred twenty-one thousand, eleven".