261666440 has 32 divisors (see below), whose sum is σ = 672857280. Its totient is φ = 89714112.

The previous prime is 261666439. The next prime is 261666463. The reversal of 261666440 is 44666162.

261666440 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (35).

It is a self number, because there is not a number n which added to its sum of digits gives 261666440.

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, 466982 + ... + 467541.

It is an arithmetic number, because the mean of its divisors is an integer number (21026790).

Almost surely, 2^261666440 is an apocalyptic number.

261666440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

261666440 is an abundant number, since it is smaller than the sum of its proper divisors (411190840).

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

261666440 is a wasteful number, since it uses less digits than its factorization.

261666440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 934541 (or 934537 counting only the distinct ones).

The product of its (nonzero) digits is 41472, while the sum is 35.

The square root of 261666440 is about 16176.1070718514. The cubic root of 261666440 is about 639.6111244371.

The spelling of 261666440 in words is "two hundred sixty-one million, six hundred sixty-six thousand, four hundred forty".