31145021 has 4 divisors (see below), whose sum is σ = 31251612. Its totient is φ = 31038432.

The previous prime is 31145011. The next prime is 31145027. The reversal of 31145021 is 12054113.

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 25452025 + 5692996 = 5045^2 + 2386^2 .

It is a cyclic number.

It is not a de Polignac number, because 31145021 - 2⁶ = 31144957 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31145027) 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, 52856 + ... + 53441.

It is an arithmetic number, because the mean of its divisors is an integer number (7812903).

Almost surely, 2^31145021 is an apocalyptic number.

It is an amenable number.

31145021 is a deficient number, since it is larger than the sum of its proper divisors (106591).

31145021 is a wasteful number, since it uses less digits than its factorization.

31145021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 106590.

The product of its (nonzero) digits is 120, while the sum is 17.

The square root of 31145021 is about 5580.7724375753. The cubic root of 31145021 is about 314.6271594434.

Adding to 31145021 its reverse (12054113), we get a palindrome (43199134).

The spelling of 31145021 in words is "thirty-one million, one hundred forty-five thousand, twenty-one".