21451123145 has 16 divisors (see below), whose sum is σ = 26809429248. Its totient is φ = 16461910080.

The previous prime is 21451123097. The next prime is 21451123157. The reversal of 21451123145 is 54132115412.

It is a happy number.

It is not a de Polignac number, because 21451123145 - 2²⁴ = 21434345929 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 803429 + ... + 829698.

It is an arithmetic number, because the mean of its divisors is an integer number (1675589328).

Almost surely, 2^21451123145 is an apocalyptic number.

It is an amenable number.

21451123145 is a deficient number, since it is larger than the sum of its proper divisors (5358306103).

21451123145 is a wasteful number, since it uses less digits than its factorization.

21451123145 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1633240.

The product of its digits is 4800, while the sum is 29.

Adding to 21451123145 its reverse (54132115412), we get a palindrome (75583238557).

The spelling of 21451123145 in words is "twenty-one billion, four hundred fifty-one million, one hundred twenty-three thousand, one hundred forty-five".