3651561 has 14 divisors (see below), whose sum is σ = 5475930. Its totient is φ = 2433888.

The previous prime is 3651559. The next prime is 3651607. The reversal of 3651561 is 1651563.

It is a happy number.

3651561 is a `hidden beast` number, since 3 + 651 + 5 + 6 + 1 = 666.

3651561 is nontrivially palindromic in base 8.

It can be written as a sum of positive squares in only one way, i.e., 3080025 + 571536 = 1755^2 + 756^2 .

It is not a de Polignac number, because 3651561 - 2¹ = 3651559 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (3651761) by changing a digit.

It is a polite number, since it can be written in 13 ways as a sum of consecutive naturals, for example, 1776 + ... + 3233.

Almost surely, 2^3651561 is an apocalyptic number.

It is an amenable number.

3651561 is a deficient number, since it is larger than the sum of its proper divisors (1824369).

3651561 is an frugal number, since it uses more digits than its factorization.

3651561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5027 (or 5012 counting only the distinct ones).

The product of its digits is 2700, while the sum is 27.

The square root of 3651561 is about 1910.9058061558. The cubic root of 3651561 is about 153.9901185541.

The spelling of 3651561 in words is "three million, six hundred fifty-one thousand, five hundred sixty-one".