261121403 has 4 divisors (see below), whose sum is σ = 264267528. Its totient is φ = 257975280.

The previous prime is 261121379. The next prime is 261121429. The reversal of 261121403 is 304121162.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 261121403 - 2²⁴ = 244344187 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (261121453) 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, 1572938 + ... + 1573103.

It is an arithmetic number, because the mean of its divisors is an integer number (66066882).

Almost surely, 2^261121403 is an apocalyptic number.

261121403 is a deficient number, since it is larger than the sum of its proper divisors (3146125).

261121403 is an equidigital number, since it uses as much as digits as its factorization.

261121403 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3146124.

The product of its (nonzero) digits is 288, while the sum is 20.

The square root of 261121403 is about 16159.2513131023. The cubic root of 261121403 is about 639.1667239817.

Adding to 261121403 its reverse (304121162), we get a palindrome (565242565).

The spelling of 261121403 in words is "two hundred sixty-one million, one hundred twenty-one thousand, four hundred three".