31138561 has 8 divisors (see below), whose sum is σ = 31633280. Its totient is φ = 30646512.

The previous prime is 31138559. The next prime is 31138637. The reversal of 31138561 is 16583113.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 31138561 - 2¹ = 31138559 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (31138531) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 48106 + ... + 48748.

It is an arithmetic number, because the mean of its divisors is an integer number (3954160).

Almost surely, 2^31138561 is an apocalyptic number.

It is an amenable number.

31138561 is a deficient number, since it is larger than the sum of its proper divisors (494719).

31138561 is an equidigital number, since it uses as much as digits as its factorization.

31138561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1335.

The product of its digits is 2160, while the sum is 28.

The square root of 31138561 is about 5580.1936346331. The cubic root of 31138561 is about 314.6054049550.

The spelling of 31138561 in words is "thirty-one million, one hundred thirty-eight thousand, five hundred sixty-one".