31121280 has 128 divisors (see below), whose sum is σ = 110282400. Its totient is φ = 8294400.

The previous prime is 31121273. The next prime is 31121281. The reversal of 31121280 is 8212113.

It is a tau number, because it is divible by the number of its divisors (128).

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31121281) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 16380 + ... + 18180.

Almost surely, 2^31121280 is an apocalyptic number.

31121280 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 31121280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (55141200).

31121280 is an abundant number, since it is smaller than the sum of its proper divisors (79161120).

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

31121280 is a wasteful number, since it uses less digits than its factorization.

31121280 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1829 (or 1811 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 18.

The square root of 31121280 is about 5578.6449967712. The cubic root of 31121280 is about 314.5471952211.

Adding to 31121280 its reverse (8212113), we get a palindrome (39333393).

The spelling of 31121280 in words is "thirty-one million, one hundred twenty-one thousand, two hundred eighty".