261633420 has 144 divisors (see below), whose sum is σ = 844028640. Its totient is φ = 65415168.

The previous prime is 261633413. The next prime is 261633433. The reversal of 261633420 is 24336162.

261633420 is a `hidden beast` number, since 2 + 6 + 1 + 633 + 4 + 20 = 666.

261633420 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 386122 + ... + 386798.

It is an arithmetic number, because the mean of its divisors is an integer number (5861310).

Almost surely, 2^261633420 is an apocalyptic number.

261633420 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 261633420, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (422014320).

261633420 is an abundant number, since it is smaller than the sum of its proper divisors (582395220).

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

261633420 is a wasteful number, since it uses less digits than its factorization.

261633420 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 824 (or 819 counting only the distinct ones).

The product of its (nonzero) digits is 5184, while the sum is 27.

The square root of 261633420 is about 16175.0863985328. The cubic root of 261633420 is about 639.5842188752.

Adding to 261633420 its reverse (24336162), we get a palindrome (285969582).

The spelling of 261633420 in words is "two hundred sixty-one million, six hundred thirty-three thousand, four hundred twenty".