661847 has 4 divisors (see below), whose sum is σ = 666816. Its totient is φ = 656880.

The previous prime is 661823. The next prime is 661849. The reversal of 661847 is 748166.

661847 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 748166 = 2 ⋅374083.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-661847 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661849) 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, 2279 + ... + 2552.

It is an arithmetic number, because the mean of its divisors is an integer number (166704).

2⁶⁶¹⁸⁴⁷ is an apocalyptic number.

661847 is a deficient number, since it is larger than the sum of its proper divisors (4969).

661847 is a wasteful number, since it uses less digits than its factorization.

661847 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4968.

The product of its digits is 8064, while the sum is 32.

The square root of 661847 is about 813.5397961993. The cubic root of 661847 is about 87.1470187798.

The spelling of 661847 in words is "six hundred sixty-one thousand, eight hundred forty-seven".