21271356551 has 4 divisors (see below), whose sum is σ = 21274274952. Its totient is φ = 21268438152.

The previous prime is 21271356473. The next prime is 21271356559. The reversal of 21271356551 is 15565317212.

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 21271356551 - 2¹⁰ = 21271355527 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21271356559) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1448240 + ... + 1462853.

It is an arithmetic number, because the mean of its divisors is an integer number (5318568738).

Almost surely, 2^21271356551 is an apocalyptic number.

21271356551 is a deficient number, since it is larger than the sum of its proper divisors (2918401).

21271356551 is an equidigital number, since it uses as much as digits as its factorization.

21271356551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2918400.

The product of its digits is 63000, while the sum is 38.

The spelling of 21271356551 in words is "twenty-one billion, two hundred seventy-one million, three hundred fifty-six thousand, five hundred fifty-one".