31040640 has 192 divisors, whose sum is σ = 113850360. Its totient is φ = 7766016.

The previous prime is 31040629. The next prime is 31040651. The reversal of 31040640 is 4604013.

It is an interprime number because it is at equal distance from previous prime (31040629) and next prime (31040651).

It can be written as a sum of positive squares in 4 ways, for example, as 21455424 + 9585216 = 4632^2 + 3096^2 .

It is a tau number, because it is divible by the number of its divisors (192).

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 97762 + ... + 98078.

Almost surely, 2^31040640 is an apocalyptic number.

31040640 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 31040640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (56925180).

31040640 is an abundant number, since it is smaller than the sum of its proper divisors (82809720).

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

31040640 is a wasteful number, since it uses less digits than its factorization.

31040640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 359 (or 344 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 18.

The square root of 31040640 is about 5571.4127472303. The cubic root of 31040640 is about 314.2752802518.

Adding to 31040640 its reverse (4604013), we get a palindrome (35644653).

The spelling of 31040640 in words is "thirty-one million, forty thousand, six hundred forty".