25666643 has 4 divisors (see below), whose sum is σ = 26782608. Its totient is φ = 24550680.

The previous prime is 25666639. The next prime is 25666661. The reversal of 25666643 is 34666652.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 25666643 - 2² = 25666639 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 25666597 and 25666606.

It is not an unprimeable number, because it can be changed into a prime (25666603) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 557948 + ... + 557993.

It is an arithmetic number, because the mean of its divisors is an integer number (6695652).

Almost surely, 2^25666643 is an apocalyptic number.

25666643 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

25666643 is a deficient number, since it is larger than the sum of its proper divisors (1115965).

25666643 is a wasteful number, since it uses less digits than its factorization.

25666643 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1115964.

The product of its digits is 155520, while the sum is 38.

The square root of 25666643 is about 5066.2257154612. The cubic root of 25666643 is about 294.9780429890.

Subtracting 25666643 from its reverse (34666652), we obtain a palindrome (9000009).

The spelling of 25666643 in words is "twenty-five million, six hundred sixty-six thousand, six hundred forty-three".