661005547 has 4 divisors (see below), whose sum is σ = 663091056. Its totient is φ = 658920040.

The previous prime is 661005511. The next prime is 661005551. The reversal of 661005547 is 745500166.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 745500166 = 2 ⋅372750083.

It is a cyclic number.

It is not a de Polignac number, because 661005547 - 2⁷ = 661005419 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (661005557) 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, 1042279 + ... + 1042912.

It is an arithmetic number, because the mean of its divisors is an integer number (165772764).

Almost surely, 2^661005547 is an apocalyptic number.

661005547 is a deficient number, since it is larger than the sum of its proper divisors (2085509).

661005547 is a wasteful number, since it uses less digits than its factorization.

661005547 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2085508.

The product of its (nonzero) digits is 25200, while the sum is 34.

The square root of 661005547 is about 25710.0281407858. The cubic root of 661005547 is about 871.1007105672.

The spelling of 661005547 in words is "six hundred sixty-one million, five thousand, five hundred forty-seven".