2563661 has 2 divisors, whose sum is σ = 2563662. Its totient is φ = 2563660.

The previous prime is 2563657. The next prime is 2563667. The reversal of 2563661 is 1663652.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1771561 + 792100 = 1331^2 + 890^2 .

It is a cyclic number.

It is not a de Polignac number, because 2563661 - 2² = 2563657 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2563667) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1281830 + 1281831.

It is an arithmetic number, because the mean of its divisors is an integer number (1281831).

2^2563661 is an apocalyptic number.

It is an amenable number.

2563661 is a deficient number, since it is larger than the sum of its proper divisors (1).

2563661 is an equidigital number, since it uses as much as digits as its factorization.

2563661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6480, while the sum is 29.

The square root of 2563661 is about 1601.1436537675. The cubic root of 2563661 is about 136.8632553186.

Subtracting from 2563661 its reverse (1663652), we obtain a palindrome (900009).

It can be divided in two parts, 25636 and 61, that multiplied together give a triangular number (1563796 = T₁₇₆₈).

The spelling of 2563661 in words is "two million, five hundred sixty-three thousand, six hundred sixty-one".