21250642177 has 4 divisors (see below), whose sum is σ = 21323170260. Its totient is φ = 21178114096.

The previous prime is 21250642159. The next prime is 21250642267. The reversal of 21250642177 is 77124605212.

It is a Cunningham number, because it is equal to 145776²+1.

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

It can be written as a sum of positive squares in 2 ways, for example, as 20106105616 + 1144536561 = 141796^2 + 33831^2 .

It is a cyclic number.

It is not a de Polignac number, because 21250642177 - 2¹¹ = 21250640129 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21250642477) 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 3 ways as a sum of consecutive naturals, for example, 36263602 + ... + 36264187.

It is an arithmetic number, because the mean of its divisors is an integer number (5330792565).

Almost surely, 2^21250642177 is an apocalyptic number.

It is an amenable number.

21250642177 is a deficient number, since it is larger than the sum of its proper divisors (72528083).

21250642177 is an equidigital number, since it uses as much as digits as its factorization.

21250642177 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 72528082.

The product of its (nonzero) digits is 47040, while the sum is 37.

The spelling of 21250642177 in words is "twenty-one billion, two hundred fifty million, six hundred forty-two thousand, one hundred seventy-seven".