661790691606 has 64 divisors (see below), whose sum is σ = 1495278600192. Its totient is φ = 193449300000.

The previous prime is 661790691599. The next prime is 661790691623. The reversal of 661790691606 is 606196097166.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 116281 + ... + 1156331.

It is an arithmetic number, because the mean of its divisors is an integer number (23363728128).

Almost surely, 2^661790691606 is an apocalyptic number.

661790691606 is a gapful number since it is divisible by the number (66) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 661790691606, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (747639300096).

661790691606 is an abundant number, since it is smaller than the sum of its proper divisors (833487908586).

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

661790691606 is a wasteful number, since it uses less digits than its factorization.

661790691606 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1040409.

The product of its (nonzero) digits is 4408992, while the sum is 57.

The spelling of 661790691606 in words is "six hundred sixty-one billion, seven hundred ninety million, six hundred ninety-one thousand, six hundred six".