31780640 has 48 divisors (see below), whose sum is σ = 75442752. Its totient is φ = 12651264.

The previous prime is 31780627. The next prime is 31780643. The reversal of 31780640 is 4608713.

31780640 = T₂₇₆ + T₂₇₇ + ... + T₅₉₅.

It is not an unprimeable number, because it can be changed into a prime (31780643) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 48797 + ... + 49443.

It is an arithmetic number, because the mean of its divisors is an integer number (1571724).

Almost surely, 2^31780640 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 31780640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37721376).

31780640 is an abundant number, since it is smaller than the sum of its proper divisors (43662112).

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

31780640 is a wasteful number, since it uses less digits than its factorization.

31780640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 969 (or 961 counting only the distinct ones).

The product of its (nonzero) digits is 4032, while the sum is 29.

The square root of 31780640 is about 5637.4320395017. The cubic root of 31780640 is about 316.7531041355.

The spelling of 31780640 in words is "thirty-one million, seven hundred eighty thousand, six hundred forty".