31745640 has 64 divisors (see below), whose sum is σ = 95981760. Its totient is φ = 8399360.

The previous prime is 31745639. The next prime is 31745641. The reversal of 31745640 is 4654713.

It is an interprime number because it is at equal distance from previous prime (31745639) and next prime (31745641).

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 31745598 and 31745607.

It is not an unprimeable number, because it can be changed into a prime (31745641) 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, 15475 + ... + 17405.

It is an arithmetic number, because the mean of its divisors is an integer number (1499715).

Almost surely, 2^31745640 is an apocalyptic number.

31745640 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 31745640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (47990880).

31745640 is an abundant number, since it is smaller than the sum of its proper divisors (64236120).

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

31745640 is a wasteful number, since it uses less digits than its factorization.

31745640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2082 (or 2078 counting only the distinct ones).

The product of its (nonzero) digits is 10080, while the sum is 30.

The square root of 31745640 is about 5634.3269340712. The cubic root of 31745640 is about 316.6367814210.

It can be divided in two parts, 31745 and 640, that added together give a triangular number (32385 = T₂₅₄).

The spelling of 31745640 in words is "thirty-one million, seven hundred forty-five thousand, six hundred forty".