21154453251 has 16 divisors (see below), whose sum is σ = 31163595264. Its totient is φ = 12696278144.

The previous prime is 21154453219. The next prime is 21154453283. The reversal of 21154453251 is 15235445112.

It is an interprime number because it is at equal distance from previous prime (21154453219) and next prime (21154453283).

It is a cyclic number.

It is not a de Polignac number, because 21154453251 - 2⁵ = 21154453219 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21154451251) by changing a digit.

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, 9016071 + ... + 9018416.

It is an arithmetic number, because the mean of its divisors is an integer number (1947724704).

Almost surely, 2^21154453251 is an apocalyptic number.

21154453251 is a deficient number, since it is larger than the sum of its proper divisors (10009142013).

21154453251 is a wasteful number, since it uses less digits than its factorization.

21154453251 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18034530.

The product of its digits is 24000, while the sum is 33.

Adding to 21154453251 its reverse (15235445112), we get a palindrome (36389898363).

The spelling of 21154453251 in words is "twenty-one billion, one hundred fifty-four million, four hundred fifty-three thousand, two hundred fifty-one".