19995864 has 64 divisors (see below), whose sum is σ = 58544640. Its totient is φ = 5571840.

The previous prime is 19995863. The next prime is 19995869. The reversal of 19995864 is 46859991.

19995864 = T₁₂₇ + T₁₂₈ + ... + T₄₉₅.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19995863) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5437 + ... + 8339.

It is an arithmetic number, because the mean of its divisors is an integer number (914760).

Almost surely, 2^19995864 is an apocalyptic number.

19995864 is a gapful number since it is divisible by the number (14) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 19995864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29272320).

19995864 is an abundant number, since it is smaller than the sum of its proper divisors (38548776).

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

19995864 is a wasteful number, since it uses less digits than its factorization.

19995864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2960 (or 2956 counting only the distinct ones).

The product of its digits is 699840, while the sum is 51.

The square root of 19995864 is about 4471.6735122323. The cubic root of 19995864 is about 271.4230489841.

The spelling of 19995864 in words is "nineteen million, nine hundred ninety-five thousand, eight hundred sixty-four".