1661488621 has 8 divisors (see below), whose sum is σ = 1790802104. Its totient is φ = 1532390400.

The previous prime is 1661488601. The next prime is 1661488627. The reversal of 1661488621 is 1268841661.

It can be written as a sum of positive squares in 4 ways, for example, as 1822500 + 1659666121 = 1350^2 + 40739^2 .

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 1661488621 - 2⁹ = 1661488109 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1661488627) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 37596 + ... + 68821.

It is an arithmetic number, because the mean of its divisors is an integer number (223850263).

Almost surely, 2^1661488621 is an apocalyptic number.

It is an amenable number.

1661488621 is a deficient number, since it is larger than the sum of its proper divisors (129313483).

1661488621 is a wasteful number, since it uses less digits than its factorization.

1661488621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 107631.

The product of its digits is 110592, while the sum is 43.

The square root of 1661488621 is about 40761.3618639024. The cubic root of 1661488621 is about 1184.4019773268.

The spelling of 1661488621 in words is "one billion, six hundred sixty-one million, four hundred eighty-eight thousand, six hundred twenty-one".