31231121221021 has 16 divisors (see below), whose sum is σ = 33138236876800. Its totient is φ = 29350406308608.

The previous prime is 31231121220931. The next prime is 31231121221037. The reversal of 31231121221021 is 12012212113213.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 31231121221021 - 2¹³ = 31231121212829 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 31231121220983 and 31231121221001.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31231121221621) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 16903201 + ... + 18659593.

It is an arithmetic number, because the mean of its divisors is an integer number (2071139804800).

Almost surely, 2^{31231121221021} is an apocalyptic number.

It is an amenable number.

31231121221021 is a deficient number, since it is larger than the sum of its proper divisors (1907115655779).

31231121221021 is a wasteful number, since it uses less digits than its factorization.

31231121221021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1763908.

The product of its (nonzero) digits is 288, while the sum is 22.

Adding to 31231121221021 its reverse (12012212113213), we get a palindrome (43243333334234).

The spelling of 31231121221021 in words is "thirty-one trillion, two hundred thirty-one billion, one hundred twenty-one million, two hundred twenty-one thousand, twenty-one".