1261611601 has 4 divisors (see below), whose sum is σ = 1266101604. Its totient is φ = 1257121600.

The previous prime is 1261611587. The next prime is 1261611683. The reversal of 1261611601 is 1061161621.

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 551122576 + 710489025 = 23476^2 + 26655^2 .

It is a cyclic number.

It is not a de Polignac number, because 1261611601 - 2¹⁵ = 1261578833 is a prime.

It is a super-3 number, since 3×1261611601³ (a number of 28 digits) contains 333 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1261411601) 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, 2244580 + ... + 2245141.

It is an arithmetic number, because the mean of its divisors is an integer number (316525401).

Almost surely, 2^1261611601 is an apocalyptic number.

It is an amenable number.

1261611601 is a deficient number, since it is larger than the sum of its proper divisors (4490003).

1261611601 is an equidigital number, since it uses as much as digits as its factorization.

1261611601 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4490002.

The product of its (nonzero) digits is 432, while the sum is 25.

The square root of 1261611601 is about 35519.1723017302. The cubic root of 1261611601 is about 1080.5425945803.

The spelling of 1261611601 in words is "one billion, two hundred sixty-one million, six hundred eleven thousand, six hundred one".