31400720 has 80 divisors (see below), whose sum is σ = 79630320. Its totient is φ = 11446272.

The previous prime is 31400701. The next prime is 31400723. The reversal of 31400720 is 2700413.

It is a happy number.

It can be written as a sum of positive squares in 8 ways, for example, as 3564544 + 27836176 = 1888^2 + 5276^2 .

It is a tau number, because it is divible by the number of its divisors (80).

It is not an unprimeable number, because it can be changed into a prime (31400723) 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, 113222 + ... + 113498.

It is an arithmetic number, because the mean of its divisors is an integer number (995379).

Almost surely, 2^31400720 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 31400720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39815160).

31400720 is an abundant number, since it is smaller than the sum of its proper divisors (48229600).

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

31400720 is a wasteful number, since it uses less digits than its factorization.

31400720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 412 (or 406 counting only the distinct ones).

The product of its (nonzero) digits is 168, while the sum is 17.

The square root of 31400720 is about 5603.6345348354. The cubic root of 31400720 is about 315.4858380075.

The spelling of 31400720 in words is "thirty-one million, four hundred thousand, seven hundred twenty".