31661540 has 48 divisors (see below), whose sum is σ = 69242880. Its totient is φ = 12147840.

The previous prime is 31661537. The next prime is 31661549. The reversal of 31661540 is 4516613.

It is not an unprimeable number, because it can be changed into a prime (31661549) 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, 138146 + ... + 138374.

It is an arithmetic number, because the mean of its divisors is an integer number (1442560).

Almost surely, 2^31661540 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 31661540, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34621440).

31661540 is an abundant number, since it is smaller than the sum of its proper divisors (37581340).

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

31661540 is a wasteful number, since it uses less digits than its factorization.

31661540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 492 (or 490 counting only the distinct ones).

The product of its (nonzero) digits is 2160, while the sum is 26.

The square root of 31661540 is about 5626.8588039865. The cubic root of 31661540 is about 316.3569245845.

The spelling of 31661540 in words is "thirty-one million, six hundred sixty-one thousand, five hundred forty".