261621420 has 48 divisors (see below), whose sum is σ = 739404288. Its totient is φ = 69112000.

The previous prime is 261621403. The next prime is 261621427. The reversal of 261621420 is 24126162.

It is not an unprimeable number, because it can be changed into a prime (261621427) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 13956 + ... + 26795.

It is an arithmetic number, because the mean of its divisors is an integer number (15404256).

Almost surely, 2^261621420 is an apocalyptic number.

261621420 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

261621420 is an abundant number, since it is smaller than the sum of its proper divisors (477782868).

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

261621420 is a wasteful number, since it uses less digits than its factorization.

261621420 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40870 (or 40868 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 24.

The square root of 261621420 is about 16174.7154534477. The cubic root of 261621420 is about 639.5744403997.

Adding to 261621420 its reverse (24126162), we get a palindrome (285747582).

The spelling of 261621420 in words is "two hundred sixty-one million, six hundred twenty-one thousand, four hundred twenty".