19999905 has 32 divisors (see below), whose sum is σ = 34245504. Its totient is φ = 9931776.

The previous prime is 19999897. The next prime is 19999909. The reversal of 19999905 is 50999991.

It is not a de Polignac number, because 19999905 - 2³ = 19999897 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (51).

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (19999909) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 26919 + ... + 27651.

It is an arithmetic number, because the mean of its divisors is an integer number (1070172).

Almost surely, 2^19999905 is an apocalyptic number.

19999905 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

19999905 is a deficient number, since it is larger than the sum of its proper divisors (14245599).

19999905 is a wasteful number, since it uses less digits than its factorization.

19999905 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 865.

The product of its (nonzero) digits is 295245, while the sum is 51.

The square root of 19999905 is about 4472.1253336641. The cubic root of 19999905 is about 271.4413318760.

The spelling of 19999905 in words is "nineteen million, nine hundred ninety-nine thousand, nine hundred five".