19979897 has 12 divisors (see below), whose sum is σ = 23573376. Its totient is φ = 16881480.

The previous prime is 19979891. The next prime is 19979899. The reversal of 19979897 is 79897991.

It is a happy number.

It is not a de Polignac number, because 19979897 - 2¹⁰ = 19978873 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 (19979891) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 608 + ... + 6350.

It is an arithmetic number, because the mean of its divisors is an integer number (1964448).

Almost surely, 2^19979897 is an apocalyptic number.

It is an amenable number.

19979897 is a deficient number, since it is larger than the sum of its proper divisors (3593479).

19979897 is an equidigital number, since it uses as much as digits as its factorization.

19979897 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5828 (or 5821 counting only the distinct ones).

The product of its digits is 2571912, while the sum is 59.

The square root of 19979897 is about 4469.8878061983. The cubic root of 19979897 is about 271.3507846086.

The spelling of 19979897 in words is "nineteen million, nine hundred seventy-nine thousand, eight hundred ninety-seven".