65001661 has 4 divisors (see below), whose sum is σ = 66067324. Its totient is φ = 63936000.

The previous prime is 65001619. The next prime is 65001689. The reversal of 65001661 is 16610056.

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

It can be written as a sum of positive squares in 2 ways, for example, as 22033636 + 42968025 = 4694^2 + 6555^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-65001661 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 (65001361) 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, 532740 + ... + 532861.

It is an arithmetic number, because the mean of its divisors is an integer number (16516831).

Almost surely, 2^65001661 is an apocalyptic number.

65001661 is a gapful number since it is divisible by the number (61) formed by its first and last digit.

It is an amenable number.

65001661 is a deficient number, since it is larger than the sum of its proper divisors (1065663).

65001661 is a wasteful number, since it uses less digits than its factorization.

65001661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1065662.

The product of its (nonzero) digits is 1080, while the sum is 25.

The square root of 65001661 is about 8062.3607584876. The cubic root of 65001661 is about 402.0760006633.

The spelling of 65001661 in words is "sixty-five million, one thousand, six hundred sixty-one".