261663500 has 48 divisors (see below), whose sum is σ = 653120832. Its totient is φ = 89712000.

The previous prime is 261663499. The next prime is 261663509. The reversal of 261663500 is 5366162.

261663500 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a super-3 number, since 3×261663500³ (a number of 26 digits) contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261663509) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 33881 + ... + 40880.

It is an arithmetic number, because the mean of its divisors is an integer number (13606684).

Almost surely, 2^261663500 is an apocalyptic number.

261663500 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

261663500 is an abundant number, since it is smaller than the sum of its proper divisors (391457332).

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

261663500 is a wasteful number, since it uses less digits than its factorization.

261663500 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 74787 (or 74775 counting only the distinct ones).

The product of its (nonzero) digits is 6480, while the sum is 29.

The square root of 261663500 is about 16176.0161968267. The cubic root of 261663500 is about 639.6087289398.

The spelling of 261663500 in words is "two hundred sixty-one million, six hundred sixty-three thousand, five hundred".