19979661 has 16 divisors (see below), whose sum is σ = 28776384. Its totient is φ = 12257664.

The previous prime is 19979657. The next prime is 19979689. The reversal of 19979661 is 16697991.

It is not a de Polignac number, because 19979661 - 2² = 19979657 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 19979661.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19979611) 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, 17665 + ... + 18761.

It is an arithmetic number, because the mean of its divisors is an integer number (1798524).

Almost surely, 2^19979661 is an apocalyptic number.

It is an amenable number.

19979661 is a deficient number, since it is larger than the sum of its proper divisors (8796723).

19979661 is a wasteful number, since it uses less digits than its factorization.

19979661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1580.

The product of its digits is 183708, while the sum is 48.

The square root of 19979661 is about 4469.8614072474. The cubic root of 19979661 is about 271.3497162174.

The spelling of 19979661 in words is "nineteen million, nine hundred seventy-nine thousand, six hundred sixty-one".