19391989 has 4 divisors (see below), whose sum is σ = 20412640. Its totient is φ = 18371340.

The previous prime is 19391969. The next prime is 19391993. The reversal of 19391989 is 98919391.

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: 98919391 = 307 ⋅322213.

It is a cyclic number.

It is not a de Polignac number, because 19391989 - 2¹¹ = 19389941 is a prime.

It is a super-2 number, since 2×19391989² = 752098474752242, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19391909) 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, 510297 + ... + 510334.

It is an arithmetic number, because the mean of its divisors is an integer number (5103160).

Almost surely, 2^19391989 is an apocalyptic number.

19391989 is a gapful number since it is divisible by the number (19) formed by its first and last digit.

It is an amenable number.

19391989 is a deficient number, since it is larger than the sum of its proper divisors (1020651).

19391989 is a wasteful number, since it uses less digits than its factorization.

19391989 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1020650.

The product of its digits is 157464, while the sum is 49.

The square root of 19391989 is about 4403.6336132789. The cubic root of 19391989 is about 268.6627476628.

The spelling of 19391989 in words is "nineteen million, three hundred ninety-one thousand, nine hundred eighty-nine".