21157310453 has 4 divisors (see below), whose sum is σ = 21160825740. Its totient is φ = 21153795168.

The previous prime is 21157310413. The next prime is 21157310459. The reversal of 21157310453 is 35401375112.

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 13107273169 + 8050037284 = 114487^2 + 89722^2 .

It is a cyclic number.

It is not a de Polignac number, because 21157310453 - 2¹⁰ = 21157309429 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21157310459) 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, 1748600 + ... + 1760657.

It is an arithmetic number, because the mean of its divisors is an integer number (5290206435).

Almost surely, 2^21157310453 is an apocalyptic number.

It is an amenable number.

21157310453 is a deficient number, since it is larger than the sum of its proper divisors (3515287).

21157310453 is an equidigital number, since it uses as much as digits as its factorization.

21157310453 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3515286.

The product of its (nonzero) digits is 12600, while the sum is 32.

Adding to 21157310453 its reverse (35401375112), we get a palindrome (56558685565).

The spelling of 21157310453 in words is "twenty-one billion, one hundred fifty-seven million, three hundred ten thousand, four hundred fifty-three".