1921861 has 4 divisors (see below), whose sum is σ = 1941772. Its totient is φ = 1901952.

The previous prime is 1921849. The next prime is 1921873. The reversal of 1921861 is 1681291.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (1921849) and next prime (1921873).

It can be written as a sum of positive squares in 2 ways, for example, as 280900 + 1640961 = 530^2 + 1281^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1921861 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1921841) 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 3 ways as a sum of consecutive naturals, for example, 9810 + ... + 10003.

It is an arithmetic number, because the mean of its divisors is an integer number (485443).

2^1921861 is an apocalyptic number.

It is an amenable number.

1921861 is a deficient number, since it is larger than the sum of its proper divisors (19911).

1921861 is an equidigital number, since it uses as much as digits as its factorization.

1921861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19910.

The product of its digits is 864, while the sum is 28.

The square root of 1921861 is about 1386.3120139420. The cubic root of 1921861 is about 124.3294439354.

The spelling of 1921861 in words is "one million, nine hundred twenty-one thousand, eight hundred sixty-one".