261954781 has 16 divisors (see below), whose sum is σ = 294368256. Its totient is φ = 231040000.

The previous prime is 261954739. The next prime is 261954787. The reversal of 261954781 is 187459162.

It is a cyclic number.

It is not a de Polignac number, because 261954781 - 2⁹ = 261954269 is a prime.

It is a super-2 number, since 2×261954781² = 137240614577515922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261954787) 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, 84621 + ... + 87661.

It is an arithmetic number, because the mean of its divisors is an integer number (18398016).

Almost surely, 2^261954781 is an apocalyptic number.

It is an amenable number.

261954781 is a deficient number, since it is larger than the sum of its proper divisors (32413475).

261954781 is a wasteful number, since it uses less digits than its factorization.

261954781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3284.

The product of its digits is 120960, while the sum is 43.

The square root of 261954781 is about 16185.0171763888. The cubic root of 261954781 is about 639.8459761188.

It can be divided in two parts, 26195 and 4781, that added together give a square (30976 = 176²).

The spelling of 261954781 in words is "two hundred sixty-one million, nine hundred fifty-four thousand, seven hundred eighty-one".