261239940 has 72 divisors (see below), whose sum is σ = 853391448. Its totient is φ = 64304640.

The previous prime is 261239929. The next prime is 261239971. The reversal of 261239940 is 49932162.

261239940 is a `hidden beast` number, since 2 + 612 + 39 + 9 + 4 + 0 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 352836 + 260887104 = 594^2 + 16152^2 .

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 261239895 and 261239904.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 53481 + ... + 58160.

It is an arithmetic number, because the mean of its divisors is an integer number (11852659).

Almost surely, 2^261239940 is an apocalyptic number.

261239940 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

261239940 is an abundant number, since it is smaller than the sum of its proper divisors (592151508).

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

261239940 is a wasteful number, since it uses less digits than its factorization.

261239940 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 111669 (or 111664 counting only the distinct ones).

The product of its (nonzero) digits is 23328, while the sum is 36.

The square root of 261239940 is about 16162.9186720716. The cubic root of 261239940 is about 639.2634266946.

It can be divided in two parts, 26123 and 9940, that added together give a palindrome (36063).

The spelling of 261239940 in words is "two hundred sixty-one million, two hundred thirty-nine thousand, nine hundred forty".