16801561 has 6 divisors (see below), whose sum is σ = 19544730. Its totient is φ = 14401296.

The previous prime is 16801553. The next prime is 16801591. The reversal of 16801561 is 16510861.

It can be written as a sum of positive squares in only one way, i.e., 9272025 + 7529536 = 3045^2 + 2744^2 .

It is not a de Polignac number, because 16801561 - 2³ = 16801553 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (16801531) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 171396 + ... + 171493.

It is an arithmetic number, because the mean of its divisors is an integer number (3257455).

Almost surely, 2^16801561 is an apocalyptic number.

It is an amenable number.

16801561 is a deficient number, since it is larger than the sum of its proper divisors (2743169).

16801561 is an equidigital number, since it uses as much as digits as its factorization.

16801561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 342903 (or 342896 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 28.

The square root of 16801561 is about 4098.9707244624. The cubic root of 16801561 is about 256.1237652283.

The spelling of 16801561 in words is "sixteen million, eight hundred one thousand, five hundred sixty-one".