1971890 has 16 divisors (see below), whose sum is σ = 3566808. Its totient is φ = 784896.

The previous prime is 1971889. The next prime is 1971901. The reversal of 1971890 is 981791.

It can be written as a sum of positive squares in 4 ways, for example, as 1825201 + 146689 = 1351^2 + 383^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 1971890.

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 7 ways as a sum of consecutive naturals, for example, 2594 + ... + 3266.

2^1971890 is an apocalyptic number.

1971890 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

1971890 is a deficient number, since it is larger than the sum of its proper divisors (1594918).

1971890 is a wasteful number, since it uses less digits than its factorization.

1971890 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 973.

The product of its (nonzero) digits is 4536, while the sum is 35.

The square root of 1971890 is about 1404.2400079758. The cubic root of 1971890 is about 125.3990447507.

Subtracting from 1971890 its reverse (981791), we obtain a palindrome (990099).

The spelling of 1971890 in words is "one million, nine hundred seventy-one thousand, eight hundred ninety".