19281661 has 4 divisors (see below), whose sum is σ = 22036192. Its totient is φ = 16527132.

The previous prime is 19281649. The next prime is 19281667. The reversal of 19281661 is 16618291.

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.

It is a cyclic number.

It is not a de Polignac number, because 19281661 - 2⁵ = 19281629 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 (19281667) 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, 1377255 + ... + 1377268.

It is an arithmetic number, because the mean of its divisors is an integer number (5509048).

Almost surely, 2^19281661 is an apocalyptic number.

It is an amenable number.

19281661 is a deficient number, since it is larger than the sum of its proper divisors (2754531).

19281661 is an equidigital number, since it uses as much as digits as its factorization.

19281661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2754530.

The product of its digits is 5184, while the sum is 34.

The square root of 19281661 is about 4391.0888171386. The cubic root of 19281661 is about 268.1522720089.

The spelling of 19281661 in words is "nineteen million, two hundred eighty-one thousand, six hundred sixty-one".