661437881 has 8 divisors (see below), whose sum is σ = 719234880. Its totient is φ = 604629072.

The previous prime is 661437877. The next prime is 661437883. The reversal of 661437881 is 188734166.

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

It is a cyclic number.

It is not a de Polignac number, because 661437881 - 2² = 661437877 is a prime.

It is a super-2 number, since 2×661437881² = 875000140843540322, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (661437883) 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, 245651 + ... + 248328.

It is an arithmetic number, because the mean of its divisors is an integer number (89904360).

Almost surely, 2^661437881 is an apocalyptic number.

It is an amenable number.

661437881 is a deficient number, since it is larger than the sum of its proper divisors (57796999).

661437881 is a wasteful number, since it uses less digits than its factorization.

661437881 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 494095.

The product of its digits is 193536, while the sum is 44.

The square root of 661437881 is about 25718.4346529877. The cubic root of 661437881 is about 871.2905851097.

The spelling of 661437881 in words is "six hundred sixty-one million, four hundred thirty-seven thousand, eight hundred eighty-one".