21154453321 has 4 divisors (see below), whose sum is σ = 21276733572. Its totient is φ = 21032173072.

The previous prime is 21154453283. The next prime is 21154453367. The reversal of 21154453321 is 12335445112.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 7822518025 + 13331935296 = 88445^2 + 115464^2 .

It is a cyclic number.

It is not a de Polignac number, because 21154453321 - 2¹⁹ = 21153929033 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21154453381) 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, 61139866 + ... + 61140211.

It is an arithmetic number, because the mean of its divisors is an integer number (5319183393).

Almost surely, 2^21154453321 is an apocalyptic number.

It is an amenable number.

21154453321 is a deficient number, since it is larger than the sum of its proper divisors (122280251).

21154453321 is a wasteful number, since it uses less digits than its factorization.

21154453321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 122280250.

The product of its digits is 14400, while the sum is 31.

Adding to 21154453321 its reverse (12335445112), we get a palindrome (33489898433).

The spelling of 21154453321 in words is "twenty-one billion, one hundred fifty-four million, four hundred fifty-three thousand, three hundred twenty-one".