661690719 has 6 divisors (see below), whose sum is σ = 955775496. Its totient is φ = 441127140.

The previous prime is 661690663. The next prime is 661690739. The reversal of 661690719 is 917096166.

It is not a de Polignac number, because 661690719 - 2⁷ = 661690591 is a prime.

It is a super-2 number, since 2×661690719² = 875669215221473922, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661690739) by changing a digit.

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 5 ways as a sum of consecutive naturals, for example, 36760587 + ... + 36760604.

It is an arithmetic number, because the mean of its divisors is an integer number (159295916).

Almost surely, 2^661690719 is an apocalyptic number.

661690719 is a deficient number, since it is larger than the sum of its proper divisors (294084777).

661690719 is a wasteful number, since it uses less digits than its factorization.

661690719 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 73521197 (or 73521194 counting only the distinct ones).

The product of its (nonzero) digits is 122472, while the sum is 45.

The square root of 661690719 is about 25723.3496846737. The cubic root of 661690719 is about 871.4015893886.

The spelling of 661690719 in words is "six hundred sixty-one million, six hundred ninety thousand, seven hundred nineteen".