261421404 has 72 divisors (see below), whose sum is σ = 649208448. Its totient is φ = 81718560.

The previous prime is 261421403. The next prime is 261421409. The reversal of 261421404 is 404124162.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261421403) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1238859 + ... + 1239069.

It is an arithmetic number, because the mean of its divisors is an integer number (9016784).

Almost surely, 2^261421404 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 261421404, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (324604224).

261421404 is an abundant number, since it is smaller than the sum of its proper divisors (387787044).

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

261421404 is a wasteful number, since it uses less digits than its factorization.

261421404 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 375 (or 306 counting only the distinct ones).

The product of its (nonzero) digits is 1536, while the sum is 24.

The square root of 261421404 is about 16168.5312876588. The cubic root of 261421404 is about 639.4114087237.

Adding to 261421404 its reverse (404124162), we get a palindrome (665545566).

The spelling of 261421404 in words is "two hundred sixty-one million, four hundred twenty-one thousand, four hundred four".