661642136 has 32 divisors (see below), whose sum is σ = 1264032000. Its totient is φ = 324621600.

The previous prime is 661642129. The next prime is 661642139. The reversal of 661642136 is 631246166.

It is a super-4 number, since 4×661642136⁴ (a number of 36 digits) contains 4444 as substring. Note that it is a super-d number also for d = 2.

It is a junction number, because it is equal to n+sod(n) for n = 661642096 and 661642105.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661642139) 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, 96965 + ... + 103563.

It is an arithmetic number, because the mean of its divisors is an integer number (39501000).

Almost surely, 2^661642136 is an apocalyptic number.

It is an amenable number.

661642136 is a deficient number, since it is larger than the sum of its proper divisors (602389864).

661642136 is a wasteful number, since it uses less digits than its factorization.

661642136 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6839 (or 6835 counting only the distinct ones).

The product of its digits is 31104, while the sum is 35.

The square root of 661642136 is about 25722.4053307617. The cubic root of 661642136 is about 871.3802620331.

The spelling of 661642136 in words is "six hundred sixty-one million, six hundred forty-two thousand, one hundred thirty-six".