19979856 has 90 divisors (see below), whose sum is σ = 60621678. Its totient is φ = 6140160.

The previous prime is 19979807. The next prime is 19979891. The reversal of 19979856 is 65897991.

19979856 = 41² + 42² + ... + 391².

It can be written as a sum of positive squares in 3 ways, for example, as 266256 + 19713600 = 516^2 + 4440^2 .

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 23926 + ... + 24746.

Almost surely, 2^19979856 is an apocalyptic number.

19979856 is a gapful number since it is divisible by the number (16) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 19979856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30310839).

19979856 is an abundant number, since it is smaller than the sum of its proper divisors (40641822).

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

19979856 is a wasteful number, since it uses less digits than its factorization.

19979856 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 861 (or 839 counting only the distinct ones).

The product of its digits is 1224720, while the sum is 54.

The square root of 19979856 is about 4469.8832199511. The cubic root of 19979856 is about 271.3505989988.

It can be divided in two parts, 1997985 and 6, that added together give a palindrome (1997991).

The spelling of 19979856 in words is "nineteen million, nine hundred seventy-nine thousand, eight hundred fifty-six".