21171007225 has 12 divisors (see below), whose sum is σ = 27393443136. Its totient is φ = 16200422480.

The previous prime is 21171007211. The next prime is 21171007321. The reversal of 21171007225 is 52270017112.

It is not a de Polignac number, because 21171007225 - 2²⁷ = 21036789497 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21171007193 and 21171007202.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 18408997 + ... + 18410146.

It is an arithmetic number, because the mean of its divisors is an integer number (2282786928).

Almost surely, 2^21171007225 is an apocalyptic number.

21171007225 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21171007225 is a deficient number, since it is larger than the sum of its proper divisors (6222435911).

21171007225 is a wasteful number, since it uses less digits than its factorization.

21171007225 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36819176 (or 36819171 counting only the distinct ones).

The product of its (nonzero) digits is 1960, while the sum is 28.

The spelling of 21171007225 in words is "twenty-one billion, one hundred seventy-one million, seven thousand, two hundred twenty-five".