21226557215 has 4 divisors (see below), whose sum is σ = 25471868664. Its totient is φ = 16981245768.

The previous prime is 21226557203. The next prime is 21226557223. The reversal of 21226557215 is 51275562212.

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 21226557215 - 2¹² = 21226553119 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2122655717 + ... + 2122655726.

It is an arithmetic number, because the mean of its divisors is an integer number (6367967166).

Almost surely, 2^21226557215 is an apocalyptic number.

21226557215 is a deficient number, since it is larger than the sum of its proper divisors (4245311449).

21226557215 is an equidigital number, since it uses as much as digits as its factorization.

21226557215 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4245311448.

The product of its digits is 84000, while the sum is 38.

The spelling of 21226557215 in words is "twenty-one billion, two hundred twenty-six million, five hundred fifty-seven thousand, two hundred fifteen".