31000000 has 98 divisors (see below), whose sum is σ = 79373984.
Its totient is φ = 12000000.
The previous prime is 30999989. The next prime is 31000003. The reversal of 31000000 is 13.
Adding to 31000000 its reverse (13), we get a palindrome (31000013).
It is a happy number.
It is a super-2 number, since 2×310000002 = 1922000000000000, which contains 22 as substring.
It is a Harshad number since it is a multiple of its sum of digits (4).
It is a nialpdrome in base 10.
It is a congruent number.
It is not an unprimeable number, because it can be changed into a prime (31000003) by changing a digit.
It is a polite number, since it can be written in 13 ways as a sum of consecutive naturals, for example, 999985 + ... + 1000015.
Almost surely, 231000000 is an apocalyptic number.
It is an amenable number.
It is a practical number, because each smaller number is the sum of distinct divisors of 31000000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39686992).
31000000 is an abundant number, since it is smaller than the sum of its proper divisors (48373984).
It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.
31000000 is an frugal number, since it uses more digits than its factorization.
31000000 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 73 (or 38 counting only the distinct ones).
The product of its (nonzero) digits is 3, while the sum is 4.
The square root of 31000000 is about 5567.7643628300.
The cubic root of 31000000 is about 314.1380652391.
The spelling of 31000000 in words is "thirty-one million", and thus it is an aban number and an uban number.