19966639 has 16 divisors (see below), whose sum is σ = 24998400. Its totient is φ = 15492960.

The previous prime is 19966633. The next prime is 19966649. The reversal of 19966639 is 93666991.

It is not a de Polignac number, because 19966639 - 2¹³ = 19958447 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 19966592 and 19966601.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19966633) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 26502 + ... + 27244.

It is an arithmetic number, because the mean of its divisors is an integer number (1562400).

Almost surely, 2^19966639 is an apocalyptic number.

19966639 is a deficient number, since it is larger than the sum of its proper divisors (5031761).

19966639 is a wasteful number, since it uses less digits than its factorization.

19966639 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1110.

The product of its digits is 472392, while the sum is 49.

The square root of 19966639 is about 4468.4045251074. The cubic root of 19966639 is about 271.2907515207.

The spelling of 19966639 in words is "nineteen million, nine hundred sixty-six thousand, six hundred thirty-nine".