4002561 has 8 divisors (see below), whose sum is σ = 5929760. Its totient is φ = 2668356.

The previous prime is 4002553. The next prime is 4002563. The reversal of 4002561 is 1652004.

4002561 = T₂₇₃ + T₂₇₄ + ... + T₃₅₃.

It is a happy number.

It is not a de Polignac number, because 4002561 - 2³ = 4002553 is a prime.

It is a Duffinian number.

4002561 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (4002563) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 74095 + ... + 74148.

It is an arithmetic number, because the mean of its divisors is an integer number (741220).

Almost surely, 2^4002561 is an apocalyptic number.

It is an amenable number.

4002561 is a deficient number, since it is larger than the sum of its proper divisors (1927199).

4002561 is a wasteful number, since it uses less digits than its factorization.

4002561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 148252 (or 148246 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 18.

The square root of 4002561 is about 2000.6401475528. The cubic root of 4002561 is about 158.7739757534.

Adding to 4002561 its reverse (1652004), we get a palindrome (5654565).

The spelling of 4002561 in words is "four million, two thousand, five hundred sixty-one".