21541646251 has 2 divisors, whose sum is σ = 21541646252. Its totient is φ = 21541646250.

The previous prime is 21541646239. The next prime is 21541646267. The reversal of 21541646251 is 15264614512.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21541646251 - 2¹³ = 21541638059 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21541646251.

It is not a weakly prime, because it can be changed into another prime (21541646221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10770823125 + 10770823126.

It is an arithmetic number, because the mean of its divisors is an integer number (10770823126).

Almost surely, 2^21541646251 is an apocalyptic number.

21541646251 is a deficient number, since it is larger than the sum of its proper divisors (1).

21541646251 is an equidigital number, since it uses as much as digits as its factorization.

21541646251 is an evil number, because the sum of its binary digits is even.

The product of its digits is 57600, while the sum is 37.

The spelling of 21541646251 in words is "twenty-one billion, five hundred forty-one million, six hundred forty-six thousand, two hundred fifty-one".