1823921661 has 4 divisors (see below), whose sum is σ = 2431895552. Its totient is φ = 1215947772.

The previous prime is 1823921557. The next prime is 1823921707. The reversal of 1823921661 is 1661293281.

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: 1661293281 = 3 ⋅553764427.

It is not a de Polignac number, because 1823921661 - 2⁹ = 1823921149 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 (1823921161) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 303986941 + ... + 303986946.

It is an arithmetic number, because the mean of its divisors is an integer number (607973888).

Almost surely, 2^1823921661 is an apocalyptic number.

It is an amenable number.

1823921661 is a deficient number, since it is larger than the sum of its proper divisors (607973891).

1823921661 is an equidigital number, since it uses as much as digits as its factorization.

1823921661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 607973890.

The product of its digits is 31104, while the sum is 39.

The square root of 1823921661 is about 42707.3958583288. The cubic root of 1823921661 is about 1221.8054565775.

The spelling of 1823921661 in words is "one billion, eight hundred twenty-three million, nine hundred twenty-one thousand, six hundred sixty-one".