263406640 has 80 divisors (see below), whose sum is σ = 701955072. Its totient is φ = 90047232.

The previous prime is 263406617. The next prime is 263406667. The reversal of 263406640 is 46604362.

It is a tau number, because it is divible by the number of its divisors (80).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 361957 + ... + 362683.

Almost surely, 2^263406640 is an apocalyptic number.

263406640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 263406640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (350977536).

263406640 is an abundant number, since it is smaller than the sum of its proper divisors (438548432).

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

263406640 is a wasteful number, since it uses less digits than its factorization.

263406640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1394 (or 1388 counting only the distinct ones).

The product of its (nonzero) digits is 20736, while the sum is 31.

The square root of 263406640 is about 16229.8071461124. The cubic root of 263406640 is about 641.0258937183.

The spelling of 263406640 in words is "two hundred sixty-three million, four hundred six thousand, six hundred forty".