261631100 has 36 divisors (see below), whose sum is σ = 568458408. Its totient is φ = 104520000.

The previous prime is 261631099. The next prime is 261631109. The reversal of 261631100 is 1136162.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261631109) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 129095 + ... + 131105.

Almost surely, 2^261631100 is an apocalyptic number.

261631100 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

261631100 is an abundant number, since it is smaller than the sum of its proper divisors (306827308).

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

261631100 is a wasteful number, since it uses less digits than its factorization.

261631100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3326 (or 3319 counting only the distinct ones).

The product of its (nonzero) digits is 216, while the sum is 20.

The square root of 261631100 is about 16175.0146831463. The cubic root of 261631100 is about 639.5823283933.

Adding to 261631100 its reverse (1136162), we get a palindrome (262767262).

The spelling of 261631100 in words is "two hundred sixty-one million, six hundred thirty-one thousand, one hundred".