19839661 has 4 divisors (see below), whose sum is σ = 19858752. Its totient is φ = 19820572.

The previous prime is 19839647. The next prime is 19839679. The reversal of 19839661 is 16693891.

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: 16693891 = 569 ⋅29339.

It is a cyclic number.

It is not a de Polignac number, because 19839661 - 2¹⁵ = 19806893 is a prime.

It is a super-2 number, since 2×19839661² = 787224297189842, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19839691) 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, 7891 + ... + 10096.

It is an arithmetic number, because the mean of its divisors is an integer number (4964688).

Almost surely, 2^19839661 is an apocalyptic number.

It is an amenable number.

19839661 is a deficient number, since it is larger than the sum of its proper divisors (19091).

19839661 is a wasteful number, since it uses less digits than its factorization.

19839661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19090.

The product of its digits is 69984, while the sum is 43.

The square root of 19839661 is about 4454.1734362281. The cubic root of 19839661 is about 270.7144361952.

The spelling of 19839661 in words is "nineteen million, eight hundred thirty-nine thousand, six hundred sixty-one".