19661904 has 30 divisors (see below), whose sum is σ = 55026426. Its totient is φ = 6553920.

The previous prime is 19661899. The next prime is 19661909. The reversal of 19661904 is 40916691.

It is an interprime number because it is at equal distance from previous prime (19661899) and next prime (19661909).

It can be written as a sum of positive squares in only one way, i.e., 12110400 + 7551504 = 3480^2 + 2748^2 .

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19661909) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 68127 + ... + 68414.

Almost surely, 2^19661904 is an apocalyptic number.

It is an amenable number.

19661904 is an abundant number, since it is smaller than the sum of its proper divisors (35364522).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

19661904 is a wasteful number, since it uses less digits than its factorization.

19661904 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 136555 (or 136546 counting only the distinct ones).

The product of its (nonzero) digits is 11664, while the sum is 36.

The square root of 19661904 is about 4434.1745567806. The cubic root of 19661904 is about 269.9035046122.

The spelling of 19661904 in words is "nineteen million, six hundred sixty-one thousand, nine hundred four".