21354661341523 has 4 divisors (see below), whose sum is σ = 21561988150768. Its totient is φ = 21147334532280.

The previous prime is 21354661341499. The next prime is 21354661341617. The reversal of 21354661341523 is 32514316645312.

It is a happy number.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21354661341523 is a prime.

It is a super-2 number, since 2×21354661341523² (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 (21354661341023) 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, 103663404468 + ... + 103663404673.

It is an arithmetic number, because the mean of its divisors is an integer number (5390497037692).

Almost surely, 2^{21354661341523} is an apocalyptic number.

21354661341523 is a deficient number, since it is larger than the sum of its proper divisors (207326809245).

21354661341523 is a wasteful number, since it uses less digits than its factorization.

21354661341523 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 207326809244.

The product of its digits is 1555200, while the sum is 46.

Adding to 21354661341523 its reverse (32514316645312), we get a palindrome (53868977986835).

The spelling of 21354661341523 in words is "twenty-one trillion, three hundred fifty-four billion, six hundred sixty-one million, three hundred forty-one thousand, five hundred twenty-three".