31220131021 has 4 divisors (see below), whose sum is σ = 31570919100. Its totient is φ = 30869342944.

The previous prime is 31220131003. The next prime is 31220131027. The reversal of 31220131021 is 12013102213.

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

It can be written as a sum of positive squares in 2 ways, for example, as 6870088996 + 24350042025 = 82886^2 + 156045^2 .

It is a cyclic number.

It is not a de Polignac number, because 31220131021 - 2²⁷ = 31085913293 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 31220130986 and 31220131004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31220131027) 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, 175393906 + ... + 175394083.

It is an arithmetic number, because the mean of its divisors is an integer number (7892729775).

Almost surely, 2^31220131021 is an apocalyptic number.

It is an amenable number.

31220131021 is a deficient number, since it is larger than the sum of its proper divisors (350788079).

31220131021 is an equidigital number, since it uses as much as digits as its factorization.

31220131021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 350788078.

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

Adding to 31220131021 its reverse (12013102213), we get a palindrome (43233233234).

The spelling of 31220131021 in words is "thirty-one billion, two hundred twenty million, one hundred thirty-one thousand, twenty-one".