661100013 has 36 divisors (see below), whose sum is σ = 1114567740. Its totient is φ = 376500096.

The previous prime is 661100009. The next prime is 661100021. The reversal of 661100013 is 310001166.

661100013 is a `hidden beast` number, since 661 + 1 + 0 + 0 + 0 + 1 + 3 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 23941449 + 637158564 = 4893^2 + 25242^2 .

It is not a de Polignac number, because 661100013 - 2² = 661100009 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661100093) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 137433 + ... + 142161.

It is an arithmetic number, because the mean of its divisors is an integer number (30960215).

Almost surely, 2^661100013 is an apocalyptic number.

661100013 is a gapful number since it is divisible by the number (63) formed by its first and last digit.

It is an amenable number.

661100013 is a deficient number, since it is larger than the sum of its proper divisors (453467727).

661100013 is a wasteful number, since it uses less digits than its factorization.

661100013 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5066 (or 5056 counting only the distinct ones).

The product of its (nonzero) digits is 108, while the sum is 18.

The square root of 661100013 is about 25711.8652182217. The cubic root of 661100013 is about 871.1422056703.

Adding to 661100013 its reverse (310001166), we get a palindrome (971101179).

The spelling of 661100013 in words is "six hundred sixty-one million, one hundred thousand, thirteen".