2891781 has 20 divisors (see below), whose sum is σ = 4549600. Its totient is φ = 1825416.

The previous prime is 2891761. The next prime is 2891789. The reversal of 2891781 is 1871982.

It is a de Polignac number, because none of the positive numbers 2^k-2891781 is a prime.

It is a super-2 number, since 2×2891781² = 16724794703922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2891789) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 600 + ... + 2478.

It is an arithmetic number, because the mean of its divisors is an integer number (227480).

2^2891781 is an apocalyptic number.

It is an amenable number.

2891781 is a deficient number, since it is larger than the sum of its proper divisors (1657819).

2891781 is a wasteful number, since it uses less digits than its factorization.

2891781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1910 (or 1901 counting only the distinct ones).

The product of its digits is 8064, while the sum is 36.

The square root of 2891781 is about 1700.5237428510. The cubic root of 2891781 is about 142.4694671425.

It can be divided in two parts, 28 and 91781, that added together give a square (91809 = 303²).

The spelling of 2891781 in words is "two million, eight hundred ninety-one thousand, seven hundred eighty-one".