26561640 has 128 divisors (see below), whose sum is σ = 92252160. Its totient is φ = 5992704.

The previous prime is 26561609. The next prime is 26561641. The reversal of 26561640 is 4616562.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 26561598 and 26561607.

It is not an unprimeable number, because it can be changed into a prime (26561641) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 86367 + ... + 86673.

It is an arithmetic number, because the mean of its divisors is an integer number (720720).

Almost surely, 2^26561640 is an apocalyptic number.

26561640 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 26561640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (46126080).

26561640 is an abundant number, since it is smaller than the sum of its proper divisors (65690520).

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

26561640 is a wasteful number, since it uses less digits than its factorization.

26561640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 431 (or 427 counting only the distinct ones).

The product of its (nonzero) digits is 8640, while the sum is 30.

The square root of 26561640 is about 5153.7985990917. The cubic root of 26561640 is about 298.3675778826.

The spelling of 26561640 in words is "twenty-six million, five hundred sixty-one thousand, six hundred forty".