261431620 has 24 divisors (see below), whose sum is σ = 553019544. Its totient is φ = 103808256.

The previous prime is 261431579. The next prime is 261431623. The reversal of 261431620 is 26134162.

It can be written as a sum of positive squares in 4 ways, for example, as 10969344 + 250462276 = 3312^2 + 15826^2 .

It is not an unprimeable number, because it can be changed into a prime (261431623) 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, 44967 + ... + 50446.

It is an arithmetic number, because the mean of its divisors is an integer number (23042481).

Almost surely, 2^261431620 is an apocalyptic number.

261431620 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

261431620 is an abundant number, since it is smaller than the sum of its proper divisors (291587924).

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

261431620 is a wasteful number, since it uses less digits than its factorization.

261431620 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 95559 (or 95557 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 25.

The square root of 261431620 is about 16168.8472068976. The cubic root of 261431620 is about 639.4197377304.

Adding to 261431620 its reverse (26134162), we get a palindrome (287565782).

The spelling of 261431620 in words is "two hundred sixty-one million, four hundred thirty-one thousand, six hundred twenty".