2001639561 has 8 divisors (see below), whose sum is σ = 2784889920. Its totient is φ = 1276407792.

The previous prime is 2001639553. The next prime is 2001639571. The reversal of 2001639561 is 1659361002.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 2001639561 - 2³ = 2001639553 is a prime.

It is not an unprimeable number, because it can be changed into a prime (2001639571) 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, 14504566 + ... + 14504703.

It is an arithmetic number, because the mean of its divisors is an integer number (348111240).

Almost surely, 2^2001639561 is an apocalyptic number.

It is an amenable number.

2001639561 is a deficient number, since it is larger than the sum of its proper divisors (783250359).

2001639561 is a wasteful number, since it uses less digits than its factorization.

2001639561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29009295.

The product of its (nonzero) digits is 9720, while the sum is 33.

The square root of 2001639561 is about 44739.6866439630. The cubic root of 2001639561 is about 1260.2652420941.

The spelling of 2001639561 in words is "two billion, one million, six hundred thirty-nine thousand, five hundred sixty-one".