21342442251 has 16 divisors (see below), whose sum is σ = 30649197600. Its totient is φ = 13132250880.

The previous prime is 21342442223. The next prime is 21342442301. The reversal of 21342442251 is 15224424312.

It is a happy number.

It is not a de Polignac number, because 21342442251 - 2¹⁵ = 21342409483 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21342442351) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 360175 + ... + 415223.

It is an arithmetic number, because the mean of its divisors is an integer number (1915574850).

Almost surely, 2^21342442251 is an apocalyptic number.

21342442251 is a deficient number, since it is larger than the sum of its proper divisors (9306755349).

21342442251 is a wasteful number, since it uses less digits than its factorization.

21342442251 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 65006.

The product of its digits is 15360, while the sum is 30.

Adding to 21342442251 its reverse (15224424312), we get a palindrome (36566866563).

The spelling of 21342442251 in words is "twenty-one billion, three hundred forty-two million, four hundred forty-two thousand, two hundred fifty-one".