661565141 has 4 divisors (see below), whose sum is σ = 682905984. Its totient is φ = 640224300.

The previous prime is 661565137. The next prime is 661565147. The reversal of 661565141 is 141565166.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 141565166 = 2 ⋅70782583.

It is a cyclic number.

It is not a de Polignac number, because 661565141 - 2² = 661565137 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 (661565147) 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 3 ways as a sum of consecutive naturals, for example, 10670375 + ... + 10670436.

It is an arithmetic number, because the mean of its divisors is an integer number (170726496).

Almost surely, 2^661565141 is an apocalyptic number.

It is an amenable number.

661565141 is a deficient number, since it is larger than the sum of its proper divisors (21340843).

661565141 is a wasteful number, since it uses less digits than its factorization.

661565141 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21340842.

The product of its digits is 21600, while the sum is 35.

The square root of 661565141 is about 25720.9086348053. The cubic root of 661565141 is about 871.3464600112.

The spelling of 661565141 in words is "six hundred sixty-one million, five hundred sixty-five thousand, one hundred forty-one".