31381506 has 48 divisors (see below), whose sum is σ = 75950784. Its totient is φ = 9653904.

The previous prime is 31381501. The next prime is 31381547. The reversal of 31381506 is 60518313.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 31381506.

It is not an unprimeable number, because it can be changed into a prime (31381501) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3835 + ... + 8801.

It is an arithmetic number, because the mean of its divisors is an integer number (1582308).

Almost surely, 2^31381506 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 31381506, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37975392).

31381506 is an abundant number, since it is smaller than the sum of its proper divisors (44569278).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

31381506 is a wasteful number, since it uses less digits than its factorization.

31381506 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4997 (or 4985 counting only the distinct ones).

The product of its (nonzero) digits is 2160, while the sum is 27.

The square root of 31381506 is about 5601.9198494802. The cubic root of 31381506 is about 315.4214766202.

Adding to 31381506 its reverse (60518313), we get a palindrome (91899819).

The spelling of 31381506 in words is "thirty-one million, three hundred eighty-one thousand, five hundred six".