19764661 has 4 divisors (see below), whose sum is σ = 22588192. Its totient is φ = 16941132.

The previous prime is 19764653. The next prime is 19764721. The reversal of 19764661 is 16646791.

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 19764661 - 2³ = 19764653 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 (19764611) 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, 1411755 + ... + 1411768.

It is an arithmetic number, because the mean of its divisors is an integer number (5647048).

Almost surely, 2^19764661 is an apocalyptic number.

It is an amenable number.

19764661 is a deficient number, since it is larger than the sum of its proper divisors (2823531).

19764661 is an equidigital number, since it uses as much as digits as its factorization.

19764661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2823530.

The product of its digits is 54432, while the sum is 40.

The square root of 19764661 is about 4445.7463940265. The cubic root of 19764661 is about 270.3728775840.

The spelling of 19764661 in words is "nineteen million, seven hundred sixty-four thousand, six hundred sixty-one".