19977864 has 16 divisors (see below), whose sum is σ = 49944720. Its totient is φ = 6659280.

The previous prime is 19977827. The next prime is 19977871. The reversal of 19977864 is 46877991.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 416182 + ... + 416229.

It is an arithmetic number, because the mean of its divisors is an integer number (3121545).

Almost surely, 2^19977864 is an apocalyptic number.

It is an amenable number.

19977864 is an abundant number, since it is smaller than the sum of its proper divisors (29966856).

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

19977864 is a wasteful number, since it uses less digits than its factorization.

19977864 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 832420 (or 832416 counting only the distinct ones).

The product of its digits is 762048, while the sum is 51.

The square root of 19977864 is about 4469.6603897835. The cubic root of 19977864 is about 271.3415807764.

The spelling of 19977864 in words is "nineteen million, nine hundred seventy-seven thousand, eight hundred sixty-four".