661684031 has 4 divisors (see below), whose sum is σ = 661896000. Its totient is φ = 661472064.

The previous prime is 661684021. The next prime is 661684073. The reversal of 661684031 is 130486166.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 661684031 - 2¹⁰ = 661683007 is a prime.

It is a super-2 number, since 2×661684031² = 875651513760817922, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 661683982 and 661684000.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661684021) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 101231 + ... + 107568.

It is an arithmetic number, because the mean of its divisors is an integer number (165474000).

Almost surely, 2^661684031 is an apocalyptic number.

661684031 is a deficient number, since it is larger than the sum of its proper divisors (211969).

661684031 is a wasteful number, since it uses less digits than its factorization.

661684031 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 211968.

The product of its (nonzero) digits is 20736, while the sum is 35.

The square root of 661684031 is about 25723.2196857236. The cubic root of 661684031 is about 871.3986534987.

The spelling of 661684031 in words is "six hundred sixty-one million, six hundred eighty-four thousand, thirty-one".