261420640 has 48 divisors (see below), whose sum is σ = 665119728. Its totient is φ = 96523776.

The previous prime is 261420637. The next prime is 261420647. The reversal of 261420640 is 46024162.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261420647) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 60762 + ... + 64921.

It is an arithmetic number, because the mean of its divisors is an integer number (13856661).

Almost surely, 2^261420640 is an apocalyptic number.

261420640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

261420640 is an abundant number, since it is smaller than the sum of its proper divisors (403699088).

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

261420640 is a wasteful number, since it uses less digits than its factorization.

261420640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 125711 (or 125703 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 25.

The square root of 261420640 is about 16168.5076615005. The cubic root of 261420640 is about 639.4107858331.

The spelling of 261420640 in words is "two hundred sixty-one million, four hundred twenty thousand, six hundred forty".