661634636 has 24 divisors (see below), whose sum is σ = 1275929424. Its totient is φ = 298267200.

The previous prime is 661634627. The next prime is 661634639. The reversal of 661634636 is 636436166.

It is a Smith number, since the sum of its digits (41) coincides with the sum of the digits of its prime factors.

It is a junction number, because it is equal to n+sod(n) for n = 661634593 and 661634602.

It is not an unprimeable number, because it can be changed into a prime (661634639) 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 7 ways as a sum of consecutive naturals, for example, 145715 + ... + 150186.

It is an arithmetic number, because the mean of its divisors is an integer number (53163726).

Almost surely, 2^661634636 is an apocalyptic number.

It is an amenable number.

661634636 is a deficient number, since it is larger than the sum of its proper divisors (614294788).

661634636 is a wasteful number, since it uses less digits than its factorization.

661634636 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 295961 (or 295959 counting only the distinct ones).

The product of its digits is 279936, while the sum is 41.

The square root of 661634636 is about 25722.2595430495. The cubic root of 661634636 is about 871.3769695299.

The spelling of 661634636 in words is "six hundred sixty-one million, six hundred thirty-four thousand, six hundred thirty-six".