19979989 has 4 divisors (see below), whose sum is σ = 20132640. Its totient is φ = 19827340.

The previous prime is 19979987. The next prime is 19980019. The reversal of 19979989 is 98997991.

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: 98997991 = 6983 ⋅14177.

It is a cyclic number.

It is not a de Polignac number, because 19979989 - 2¹ = 19979987 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19979987) 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, 76129 + ... + 76390.

It is an arithmetic number, because the mean of its divisors is an integer number (5033160).

Almost surely, 2^19979989 is an apocalyptic number.

It is an amenable number.

19979989 is a deficient number, since it is larger than the sum of its proper divisors (152651).

19979989 is a wasteful number, since it uses less digits than its factorization.

19979989 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 152650.

The product of its digits is 3306744, while the sum is 61.

The square root of 19979989 is about 4469.8980972725. The cubic root of 19979989 is about 271.3512010978.

The spelling of 19979989 in words is "nineteen million, nine hundred seventy-nine thousand, nine hundred eighty-nine".