1616561 has 4 divisors (see below), whose sum is σ = 1643124. Its totient is φ = 1590000.

The previous prime is 1616551. The next prime is 1616569. The reversal of 1616561 is 1656161.

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 250000 + 1366561 = 500^2 + 1169^2 .

It is a cyclic number.

It is not a de Polignac number, because 1616561 - 2⁶ = 1616497 is a prime.

It is a super-2 number, since 2×1616561² = 5226538933442, which contains 22 as substring.

It is an alternating number because its digits alternate between odd and even.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1616561.

It is not an unprimeable number, because it can be changed into a prime (1616569) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13190 + ... + 13311.

It is an arithmetic number, because the mean of its divisors is an integer number (410781).

2^1616561 is an apocalyptic number.

It is an amenable number.

1616561 is a deficient number, since it is larger than the sum of its proper divisors (26563).

1616561 is an equidigital number, since it uses as much as digits as its factorization.

1616561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26562.

The product of its digits is 1080, while the sum is 26.

The square root of 1616561 is about 1271.4405216132. The cubic root of 1616561 is about 117.3628640016.

The spelling of 1616561 in words is "one million, six hundred sixteen thousand, five hundred sixty-one".