26661978 has 144 divisors (see below), whose sum is σ = 74337120. Its totient is φ = 6858432.

The previous prime is 26661949. The next prime is 26661979. The reversal of 26661978 is 87916662.

It is a super-2 number, since 2×26661978² = 1421722141744968, which contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (26661979) by changing a digit.

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 71 ways as a sum of consecutive naturals, for example, 620025 + ... + 620067.

It is an arithmetic number, because the mean of its divisors is an integer number (516230).

Almost surely, 2^26661978 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 26661978, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37168560).

26661978 is an abundant number, since it is smaller than the sum of its proper divisors (47675142).

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

26661978 is a wasteful number, since it uses less digits than its factorization.

26661978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 121 (or 111 counting only the distinct ones).

The product of its digits is 217728, while the sum is 45.

The square root of 26661978 is about 5163.5237967884. The cubic root of 26661978 is about 298.7428055666.

The spelling of 26661978 in words is "twenty-six million, six hundred sixty-one thousand, nine hundred seventy-eight".