261816401 has 8 divisors (see below), whose sum is σ = 326420544. Its totient is φ = 204012720.

The previous prime is 261816391. The next prime is 261816407. The reversal of 261816401 is 104618162.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-261816401 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (261816407) 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, 1700030 + ... + 1700183.

It is an arithmetic number, because the mean of its divisors is an integer number (40802568).

Almost surely, 2^261816401 is an apocalyptic number.

It is an amenable number.

261816401 is a deficient number, since it is larger than the sum of its proper divisors (64604143).

261816401 is a wasteful number, since it uses less digits than its factorization.

261816401 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3400231.

The product of its (nonzero) digits is 2304, while the sum is 29.

The square root of 261816401 is about 16180.7416702696. The cubic root of 261816401 is about 639.7332881179.

The spelling of 261816401 in words is "two hundred sixty-one million, eight hundred sixteen thousand, four hundred one".