31220245640 has 16 divisors (see below), whose sum is σ = 70245552780. Its totient is φ = 12488098240.

The previous prime is 31220245633. The next prime is 31220245649. The reversal of 31220245640 is 4654202213.

It can be written as a sum of positive squares in 2 ways, for example, as 31213702276 + 6543364 = 176674^2 + 2558^2 .

It is not an unprimeable number, because it can be changed into a prime (31220245649) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 390253031 + ... + 390253110.

Almost surely, 2^31220245640 is an apocalyptic number.

It is an amenable number.

31220245640 is an abundant number, since it is smaller than the sum of its proper divisors (39025307140).

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

31220245640 is a wasteful number, since it uses less digits than its factorization.

31220245640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 780506152 (or 780506148 counting only the distinct ones).

The product of its (nonzero) digits is 11520, while the sum is 29.

Adding to 31220245640 its reverse (4654202213), we get a palindrome (35874447853).

The spelling of 31220245640 in words is "thirty-one billion, two hundred twenty million, two hundred forty-five thousand, six hundred forty".