31378993 has 4 divisors (see below), whose sum is σ = 31398948. Its totient is φ = 31359040.

The previous prime is 31378987. The next prime is 31379003. The reversal of 31378993 is 39987313.

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 21594609 + 9784384 = 4647^2 + 3128^2 .

It is a cyclic number.

It is not a de Polignac number, because 31378993 - 2⁵ = 31378961 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (31378933) 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, 7396 + ... + 10837.

It is an arithmetic number, because the mean of its divisors is an integer number (7849737).

Almost surely, 2^31378993 is an apocalyptic number.

It is an amenable number.

31378993 is a deficient number, since it is larger than the sum of its proper divisors (19955).

31378993 is a wasteful number, since it uses less digits than its factorization.

31378993 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19954.

The product of its digits is 122472, while the sum is 43.

The square root of 31378993 is about 5601.6955468858. The cubic root of 31378993 is about 315.4130568487.

The spelling of 31378993 in words is "thirty-one million, three hundred seventy-eight thousand, nine hundred ninety-three".