1961781 has 4 divisors (see below), whose sum is σ = 2615712. Its totient is φ = 1307852.

The previous prime is 1961767. The next prime is 1961797. The reversal of 1961781 is 1871691.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1961781 - 2⁷ = 1961653 is a prime.

It is a super-2 number, since 2×1961781² = 7697169383922, which contains 22 as substring.

It is a D-number.

1961781 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1961741) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 326961 + ... + 326966.

It is an arithmetic number, because the mean of its divisors is an integer number (653928).

2^1961781 is an apocalyptic number.

It is an amenable number.

1961781 is a deficient number, since it is larger than the sum of its proper divisors (653931).

1961781 is an equidigital number, since it uses as much as digits as its factorization.

1961781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 653930.

The product of its digits is 3024, while the sum is 33.

The square root of 1961781 is about 1400.6359269989. The cubic root of 1961781 is about 125.1843892046.

The spelling of 1961781 in words is "one million, nine hundred sixty-one thousand, seven hundred eighty-one".