2145681 has 12 divisors (see below), whose sum is σ = 3206580. Its totient is φ = 1380960.

The previous prime is 2145677. The next prime is 2145683. The reversal of 2145681 is 1865412.

It can be written as a sum of positive squares in 2 ways, for example, as 1648656 + 497025 = 1284^2 + 705^2 .

It is not a de Polignac number, because 2145681 - 2² = 2145677 is a prime.

It is a super-2 number, since 2×2145681² = 9207893907522, which contains 22 as substring.

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (2145683) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3850 + ... + 4371.

It is an arithmetic number, because the mean of its divisors is an integer number (267215).

2^2145681 is an apocalyptic number.

It is an amenable number.

2145681 is a deficient number, since it is larger than the sum of its proper divisors (1060899).

2145681 is a wasteful number, since it uses less digits than its factorization.

2145681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8256 (or 8253 counting only the distinct ones).

The product of its digits is 1920, while the sum is 27.

The square root of 2145681 is about 1464.8143227044. The cubic root of 2145681 is about 128.9798057446.

The spelling of 2145681 in words is "two million, one hundred forty-five thousand, six hundred eighty-one".