6401561 has 4 divisors (see below), whose sum is σ = 6411300. Its totient is φ = 6391824.

The previous prime is 6401557. The next prime is 6401569. The reversal of 6401561 is 1651046.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 4243600 + 2157961 = 2060^2 + 1469^2 .

It is a cyclic number.

It is not a de Polignac number, because 6401561 - 2² = 6401557 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (6401569) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3806 + ... + 5223.

It is an arithmetic number, because the mean of its divisors is an integer number (1602825).

Almost surely, 2^6401561 is an apocalyptic number.

It is an amenable number.

6401561 is a deficient number, since it is larger than the sum of its proper divisors (9739).

6401561 is an equidigital number, since it uses as much as digits as its factorization.

6401561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9738.

The product of its (nonzero) digits is 720, while the sum is 23.

The square root of 6401561 is about 2530.1306290387. The cubic root of 6401561 is about 185.6786469511.

The spelling of 6401561 in words is "six million, four hundred one thousand, five hundred sixty-one".