31151221020145 has 4 divisors (see below), whose sum is σ = 37381465224180. Its totient is φ = 24920976816112.

The previous prime is 31151221020119. The next prime is 31151221020149. The reversal of 31151221020145 is 54102012215113.

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 8875775642176 + 22275445377969 = 2979224^2 + 4719687^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-31151221020145 is a prime.

It is not an unprimeable number, because it can be changed into a prime (31151221020149) 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, 3115122102010 + ... + 3115122102019.

It is an arithmetic number, because the mean of its divisors is an integer number (9345366306045).

Almost surely, 2^{31151221020145} is an apocalyptic number.

It is an amenable number.

31151221020145 is a deficient number, since it is larger than the sum of its proper divisors (6230244204035).

31151221020145 is an equidigital number, since it uses as much as digits as its factorization.

31151221020145 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6230244204034.

The product of its (nonzero) digits is 2400, while the sum is 28.

Adding to 31151221020145 its reverse (54102012215113), we get a palindrome (85253233235258).

The spelling of 31151221020145 in words is "thirty-one trillion, one hundred fifty-one billion, two hundred twenty-one million, twenty thousand, one hundred forty-five".