661343986 has 4 divisors (see below), whose sum is σ = 992015982. Its totient is φ = 330671992.

The previous prime is 661343983. The next prime is 661343989. The reversal of 661343986 is 689343166.

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

It is an interprime number because it is at equal distance from previous prime (661343983) and next prime (661343989).

It can be written as a sum of positive squares in only one way, i.e., 613305225 + 48038761 = 24765^2 + 6931^2 .

It is not an unprimeable number, because it can be changed into a prime (661343983) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 165335995 + ... + 165335998.

Almost surely, 2^661343986 is an apocalyptic number.

661343986 is a deficient number, since it is larger than the sum of its proper divisors (330671996).

661343986 is a wasteful number, since it uses less digits than its factorization.

661343986 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 330671995.

The product of its digits is 559872, while the sum is 46.

The square root of 661343986 is about 25716.6091466196. The cubic root of 661343986 is about 871.2493548832.

The spelling of 661343986 in words is "six hundred sixty-one million, three hundred forty-three thousand, nine hundred eighty-six".