21450340251 has 24 divisors (see below), whose sum is σ = 31863078000. Its totient is φ = 13899866112.

The previous prime is 21450340213. The next prime is 21450340309. The reversal of 21450340251 is 15204305412.

21450340251 is a `hidden beast` number, since 21 + 4 + 50 + 340 + 251 = 666.

It is not a de Polignac number, because 21450340251 - 2⁷ = 21450340123 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21450340211) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 179686 + ... + 274203.

It is an arithmetic number, because the mean of its divisors is an integer number (1327628250).

Almost surely, 2^21450340251 is an apocalyptic number.

21450340251 is a deficient number, since it is larger than the sum of its proper divisors (10412737749).

21450340251 is a wasteful number, since it uses less digits than its factorization.

21450340251 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 454043 (or 454040 counting only the distinct ones).

The product of its (nonzero) digits is 4800, while the sum is 27.

Adding to 21450340251 its reverse (15204305412), we get a palindrome (36654645663).

The spelling of 21450340251 in words is "twenty-one billion, four hundred fifty million, three hundred forty thousand, two hundred fifty-one".