19979999 has 8 divisors (see below), whose sum is σ = 21673680. Its totient is φ = 18308736.

The previous prime is 19979987. The next prime is 19980019. The reversal of 19979999 is 99997991.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-19979999 is a prime.

It is a Duffinian number.

19979999 is a modest number, since divided by 9999 gives 1997 as remainder.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19979909) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3722 + ... + 7335.

It is an arithmetic number, because the mean of its divisors is an integer number (2709210).

Almost surely, 2^19979999 is an apocalyptic number.

19979999 is a deficient number, since it is larger than the sum of its proper divisors (1693681).

19979999 is a wasteful number, since it uses less digits than its factorization.

19979999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11209.

The product of its digits is 3720087, while the sum is 62.

The square root of 19979999 is about 4469.8992158661. The cubic root of 19979999 is about 271.3512463683.

The spelling of 19979999 in words is "nineteen million, nine hundred seventy-nine thousand, nine hundred ninety-nine".