1654611661 has 4 divisors (see below), whose sum is σ = 1655434012. Its totient is φ = 1653789312.

The previous prime is 1654611583. The next prime is 1654611667. The reversal of 1654611661 is 1661164561.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1661164561 = 7 ⋅237309223.

It can be written as a sum of positive squares in 2 ways, for example, as 1280924100 + 373687561 = 35790^2 + 19331^2 .

It is a cyclic number.

It is not a de Polignac number, because 1654611661 - 2²¹ = 1652514509 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 1654611661.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1654611667) 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, 408150 + ... + 412183.

It is an arithmetic number, because the mean of its divisors is an integer number (413858503).

Almost surely, 2^1654611661 is an apocalyptic number.

It is an amenable number.

1654611661 is a deficient number, since it is larger than the sum of its proper divisors (822351).

1654611661 is an equidigital number, since it uses as much as digits as its factorization.

1654611661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 822350.

The product of its digits is 25920, while the sum is 37.

The square root of 1654611661 is about 40676.9180371375. The cubic root of 1654611661 is about 1182.7656237523.

The spelling of 1654611661 in words is "one billion, six hundred fifty-four million, six hundred eleven thousand, six hundred sixty-one".