21503223253451 has 4 divisors (see below), whose sum is σ = 21511255838592. Its totient is φ = 21495190668312.

The previous prime is 21503223253439. The next prime is 21503223253459. The reversal of 21503223253451 is 15435232230512.

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

It is a cyclic number.

It is not a de Polignac number, because 21503223253451 - 2¹⁸ = 21503222991307 is a prime.

It is a super-2 number, since 2×21503223253451² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21503223253459) 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, 4016288555 + ... + 4016293908.

It is an arithmetic number, because the mean of its divisors is an integer number (5377813959648).

Almost surely, 2^{21503223253451} is an apocalyptic number.

21503223253451 is a deficient number, since it is larger than the sum of its proper divisors (8032585141).

21503223253451 is an equidigital number, since it uses as much as digits as its factorization.

21503223253451 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8032585140.

The product of its (nonzero) digits is 216000, while the sum is 38.

Adding to 21503223253451 its reverse (15435232230512), we get a palindrome (36938455483963).

The spelling of 21503223253451 in words is "twenty-one trillion, five hundred three billion, two hundred twenty-three million, two hundred fifty-three thousand, four hundred fifty-one".