19701990 has 96 divisors (see below), whose sum is σ = 63887616. Its totient is φ = 4092480.

The previous prime is 19701947. The next prime is 19702009. The reversal of 19701990 is 9910791.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

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 47 ways as a sum of consecutive naturals, for example, 5509 + ... + 8351.

It is an arithmetic number, because the mean of its divisors is an integer number (665496).

Almost surely, 2^19701990 is an apocalyptic number.

19701990 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 19701990, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31943808).

19701990 is an abundant number, since it is smaller than the sum of its proper divisors (44185626).

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

19701990 is a wasteful number, since it uses less digits than its factorization.

19701990 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2874 (or 2871 counting only the distinct ones).

The product of its (nonzero) digits is 5103, while the sum is 36.

The square root of 19701990 is about 4438.6923750132. The cubic root of 19701990 is about 270.0868033660.

The spelling of 19701990 in words is "nineteen million, seven hundred one thousand, nine hundred ninety".