261311001 has 16 divisors (see below), whose sum is σ = 398466048. Its totient is φ = 149216400.

The previous prime is 261310993. The next prime is 261311077. The reversal of 261311001 is 100113162.

261311001 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 261311001 - 2³ = 261310993 is a prime.

It is not an unprimeable number, because it can be changed into a prime (261311801) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 34596 + ... + 41466.

It is an arithmetic number, because the mean of its divisors is an integer number (24904128).

Almost surely, 2^261311001 is an apocalyptic number.

261311001 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

261311001 is a deficient number, since it is larger than the sum of its proper divisors (137155047).

261311001 is a wasteful number, since it uses less digits than its factorization.

261311001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8692.

The product of its (nonzero) digits is 36, while the sum is 15.

The square root of 261311001 is about 16165.1167951240. The cubic root of 261311001 is about 639.3213843715.

Adding to 261311001 its reverse (100113162), we get a palindrome (361424163).

The spelling of 261311001 in words is "two hundred sixty-one million, three hundred eleven thousand, one".