31399789 has 4 divisors (see below), whose sum is σ = 31710780. Its totient is φ = 31088800.

The previous prime is 31399787. The next prime is 31399829. The reversal of 31399789 is 98799313.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 98799313 = 359 ⋅275207.

It can be written as a sum of positive squares in 2 ways, for example, as 19873764 + 11526025 = 4458^2 + 3395^2 .

It is a cyclic number.

It is not a de Polignac number, because 31399789 - 2¹ = 31399787 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31399787) 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, 155344 + ... + 155545.

It is an arithmetic number, because the mean of its divisors is an integer number (7927695).

Almost surely, 2^31399789 is an apocalyptic number.

It is an amenable number.

31399789 is a deficient number, since it is larger than the sum of its proper divisors (310991).

31399789 is a wasteful number, since it uses less digits than its factorization.

31399789 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 310990.

The product of its digits is 367416, while the sum is 49.

The square root of 31399789 is about 5603.5514631348. The cubic root of 31399789 is about 315.4827200299.

The spelling of 31399789 in words is "thirty-one million, three hundred ninety-nine thousand, seven hundred eighty-nine".