19912861 has 4 divisors (see below), whose sum is σ = 19956892. Its totient is φ = 19868832.

The previous prime is 19912859. The next prime is 19912877. The reversal of 19912861 is 16821991.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 6996025 + 12916836 = 2645^2 + 3594^2 .

It is a cyclic number.

It is not a de Polignac number, because 19912861 - 2¹ = 19912859 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 19912861.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19912811) 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, 21330 + ... + 22243.

It is an arithmetic number, because the mean of its divisors is an integer number (4989223).

Almost surely, 2^19912861 is an apocalyptic number.

It is an amenable number.

19912861 is a deficient number, since it is larger than the sum of its proper divisors (44031).

19912861 is an equidigital number, since it uses as much as digits as its factorization.

19912861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 44030.

The product of its digits is 7776, while the sum is 37.

The square root of 19912861 is about 4462.3828836172. The cubic root of 19912861 is about 271.0469683437.

The spelling of 19912861 in words is "nineteen million, nine hundred twelve thousand, eight hundred sixty-one".