661335638 has 8 divisors (see below), whose sum is σ = 992266632. Its totient is φ = 330580096.

The previous prime is 661335611. The next prime is 661335659. The reversal of 661335638 is 836533166.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a junction number, because it is equal to n+sod(n) for n = 661335595 and 661335604.

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 3 ways as a sum of consecutive naturals, for example, 33995 + ... + 49782.

It is an arithmetic number, because the mean of its divisors is an integer number (124033329).

Almost surely, 2^661335638 is an apocalyptic number.

661335638 is a deficient number, since it is larger than the sum of its proper divisors (330930994).

661335638 is a wasteful number, since it uses less digits than its factorization.

661335638 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 87726.

The product of its digits is 233280, while the sum is 41.

The square root of 661335638 is about 25716.4468385506. The cubic root of 661335638 is about 871.2456890046.

The spelling of 661335638 in words is "six hundred sixty-one million, three hundred thirty-five thousand, six hundred thirty-eight".