31661618 has 4 divisors (see below), whose sum is σ = 47492430. Its totient is φ = 15830808.

The previous prime is 31661611. The next prime is 31661681. The reversal of 31661618 is 81616613.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 24137569 + 7524049 = 4913^2 + 2743^2 .

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (31661611) 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 as a sum of consecutive naturals, namely, 7915403 + ... + 7915406.

Almost surely, 2^31661618 is an apocalyptic number.

31661618 is a deficient number, since it is larger than the sum of its proper divisors (15830812).

31661618 is a wasteful number, since it uses less digits than its factorization.

31661618 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15830811.

The product of its digits is 5184, while the sum is 32.

The square root of 31661618 is about 5626.8657350251. The cubic root of 31661618 is about 316.3571843720.

The spelling of 31661618 in words is "thirty-one million, six hundred sixty-one thousand, six hundred eighteen".