1661206501 has 8 divisors (see below), whose sum is σ = 1707833240. Its totient is φ = 1614670848.

The previous prime is 1661206453. The next prime is 1661206531. The reversal of 1661206501 is 1056021661.

It can be written as a sum of positive squares in 4 ways, for example, as 538286401 + 1122920100 = 23201^2 + 33510^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1661206501 - 2⁷ = 1661206373 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1661206501.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1661206531) 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 7 ways as a sum of consecutive naturals, for example, 15085 + ... + 59581.

It is an arithmetic number, because the mean of its divisors is an integer number (213479155).

Almost surely, 2^1661206501 is an apocalyptic number.

It is an amenable number.

1661206501 is a deficient number, since it is larger than the sum of its proper divisors (46626739).

1661206501 is a wasteful number, since it uses less digits than its factorization.

1661206501 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 45543.

The product of its (nonzero) digits is 2160, while the sum is 28.

The square root of 1661206501 is about 40757.9010867832. The cubic root of 1661206501 is about 1184.3349365627.

The spelling of 1661206501 in words is "one billion, six hundred sixty-one million, two hundred six thousand, five hundred one".