816661544 has 16 divisors (see below), whose sum is σ = 1531559220. Its totient is φ = 408245760.

The previous prime is 816661541. The next prime is 816661561. The reversal of 816661544 is 445166618.

It can be written as a sum of positive squares in 2 ways, for example, as 743216644 + 73444900 = 27262^2 + 8570^2 .

It is not an unprimeable number, because it can be changed into a prime (816661541) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 51704 + ... + 65624.

Almost surely, 2^816661544 is an apocalyptic number.

It is an amenable number.

816661544 is a deficient number, since it is larger than the sum of its proper divisors (714897676).

816661544 is a wasteful number, since it uses less digits than its factorization.

816661544 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21260 (or 21256 counting only the distinct ones).

The product of its digits is 138240, while the sum is 41.

The square root of 816661544 is about 28577.2907043337. The cubic root of 816661544 is about 934.7182061382.

The spelling of 816661544 in words is "eight hundred sixteen million, six hundred sixty-one thousand, five hundred forty-four".