31531013 has 4 divisors (see below), whose sum is σ = 33190560. Its totient is φ = 29871468.

The previous prime is 31531001. The next prime is 31531057. The reversal of 31531013 is 31013513.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 31013513 = 197 ⋅157429.

It is a cyclic number.

It is not a de Polignac number, because 31531013 - 2¹⁴ = 31514629 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 31530982 and 31531000.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31531063) 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, 829745 + ... + 829782.

It is an arithmetic number, because the mean of its divisors is an integer number (8297640).

Almost surely, 2^31531013 is an apocalyptic number.

It is an amenable number.

31531013 is a deficient number, since it is larger than the sum of its proper divisors (1659547).

31531013 is a wasteful number, since it uses less digits than its factorization.

31531013 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1659546.

The product of its (nonzero) digits is 135, while the sum is 17.

The square root of 31531013 is about 5615.2482580915. The cubic root of 31531013 is about 315.9215909984.

Adding to 31531013 its reverse (31013513), we get a palindrome (62544526).

The spelling of 31531013 in words is "thirty-one million, five hundred thirty-one thousand, thirteen".