261840864 has 48 divisors (see below), whose sum is σ = 688165632. Its totient is φ = 87174528.

The previous prime is 261840857. The next prime is 261840871. The reversal of 261840864 is 468048162.

It is an interprime number because it is at equal distance from previous prime (261840857) and next prime (261840871).

It is a tau number, because it is divible by the number of its divisors (48).

It is a congruent number.

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, 151107 + ... + 152829.

It is an arithmetic number, because the mean of its divisors is an integer number (14336784).

Almost surely, 2^261840864 is an apocalyptic number.

261840864 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

261840864 is an abundant number, since it is smaller than the sum of its proper divisors (426324768).

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

261840864 is a wasteful number, since it uses less digits than its factorization.

261840864 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3319 (or 3311 counting only the distinct ones).

The product of its (nonzero) digits is 73728, while the sum is 39.

The square root of 261840864 is about 16181.4975821152. The cubic root of 261840864 is about 639.7532121410.

The spelling of 261840864 in words is "two hundred sixty-one million, eight hundred forty thousand, eight hundred sixty-four".