261520520 has 32 divisors (see below), whose sum is σ = 623035800. Its totient is φ = 98454528.

The previous prime is 261520517. The next prime is 261520543. The reversal of 261520520 is 25025162.

It can be written as a sum of positive squares in 4 ways, for example, as 152819044 + 108701476 = 12362^2 + 10426^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 191615 + ... + 192974.

Almost surely, 2^261520520 is an apocalyptic number.

261520520 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

261520520 is an abundant number, since it is smaller than the sum of its proper divisors (361515280).

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

261520520 is a wasteful number, since it uses less digits than its factorization.

261520520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 384617 (or 384613 counting only the distinct ones).

The product of its (nonzero) digits is 1200, while the sum is 23.

The square root of 261520520 is about 16171.5960869668. The cubic root of 261520520 is about 639.4922078886.

Adding to 261520520 its reverse (25025162), we get a palindrome (286545682).

The spelling of 261520520 in words is "two hundred sixty-one million, five hundred twenty thousand, five hundred twenty".