31280400 has 90 divisors (see below), whose sum is σ = 108564170. Its totient is φ = 8340480.

The previous prime is 31280369. The next prime is 31280401. The reversal of 31280400 is 408213.

It is a happy number.

It can be written as a sum of positive squares in 3 ways, for example, as 6718464 + 24561936 = 2592^2 + 4956^2 .

It is a tau number, because it is divible by the number of its divisors (90).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is not an unprimeable number, because it can be changed into a prime (31280401) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 745 + ... + 7944.

Almost surely, 2^31280400 is an apocalyptic number.

31280400 is a gapful number since it is divisible by the number (30) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 31280400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (54282085).

31280400 is an abundant number, since it is smaller than the sum of its proper divisors (77283770).

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

31280400 is a wasteful number, since it uses less digits than its factorization.

31280400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8713 (or 8699 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 18.

The square root of 31280400 is about 5592.8883414565. Note that the first 3 decimals coincide. The cubic root of 31280400 is about 315.0823669716.

Adding to 31280400 its reverse (408213), we get a palindrome (31688613).

The spelling of 31280400 in words is "thirty-one million, two hundred eighty thousand, four hundred".