19805890 has 32 divisors (see below), whose sum is σ = 38719296. Its totient is φ = 7250880.

The previous prime is 19805881. The next prime is 19805893. The reversal of 19805890 is 9850891.

It is not an unprimeable number, because it can be changed into a prime (19805893) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 16449 + ... + 17611.

It is an arithmetic number, because the mean of its divisors is an integer number (1209978).

Almost surely, 2^19805890 is an apocalyptic number.

19805890 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

19805890 is a deficient number, since it is larger than the sum of its proper divisors (18913406).

19805890 is a wasteful number, since it uses less digits than its factorization.

19805890 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1314.

The product of its (nonzero) digits is 25920, while the sum is 40.

The square root of 19805890 is about 4450.3808825762. The cubic root of 19805890 is about 270.5607459101.

The spelling of 19805890 in words is "nineteen million, eight hundred five thousand, eight hundred ninety".