261721304 has 32 divisors (see below), whose sum is σ = 529200000. Its totient is φ = 120628992.

The previous prime is 261721303. The next prime is 261721319. The reversal of 261721304 is 403127162.

It is a Harshad number since it is a multiple of its sum of digits (26).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261721303) 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, 107897 + ... + 110295.

It is an arithmetic number, because the mean of its divisors is an integer number (16537500).

Almost surely, 2^261721304 is an apocalyptic number.

It is an amenable number.

261721304 is an abundant number, since it is smaller than the sum of its proper divisors (267478696).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

261721304 is a wasteful number, since it uses less digits than its factorization.

261721304 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3467 (or 3463 counting only the distinct ones).

The product of its (nonzero) digits is 2016, while the sum is 26.

The square root of 261721304 is about 16177.8028174409. The cubic root of 261721304 is about 639.6558240586.

Adding to 261721304 its reverse (403127162), we get a palindrome (664848466).

The spelling of 261721304 in words is "two hundred sixty-one million, seven hundred twenty-one thousand, three hundred four".