21661042026225 has 24 divisors (see below), whose sum is σ = 40929054648640. Its totient is φ = 9902190640320.

The previous prime is 21661042026199. The next prime is 21661042026277. The reversal of 21661042026225 is 52262024016612.

It is not a de Polignac number, because 21661042026225 - 2¹⁰ = 21661042025201 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 20629563310 + ... + 20629564359.

Almost surely, 2^{21661042026225} is an apocalyptic number.

21661042026225 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21661042026225 is a deficient number, since it is larger than the sum of its proper divisors (19268012622415).

21661042026225 is a wasteful number, since it uses less digits than its factorization.

21661042026225 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 41259127689 (or 41259127684 counting only the distinct ones).

The product of its (nonzero) digits is 138240, while the sum is 39.

The spelling of 21661042026225 in words is "twenty-one trillion, six hundred sixty-one billion, forty-two million, twenty-six thousand, two hundred twenty-five".