261321554 has 16 divisors (see below), whose sum is σ = 444353280. Its totient is φ = 114261840.

The previous prime is 261321553. The next prime is 261321559. The reversal of 261321554 is 455123162.

It is not an unprimeable number, because it can be changed into a prime (261321553) 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, 264002 + ... + 264989.

It is an arithmetic number, because the mean of its divisors is an integer number (27772080).

Almost surely, 2^261321554 is an apocalyptic number.

261321554 is a deficient number, since it is larger than the sum of its proper divisors (183031726).

261321554 is a wasteful number, since it uses less digits than its factorization.

261321554 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 529025.

The product of its digits is 7200, while the sum is 29.

The square root of 261321554 is about 16165.4432045645. The cubic root of 261321554 is about 639.3299905505.

The spelling of 261321554 in words is "two hundred sixty-one million, three hundred twenty-one thousand, five hundred fifty-four".