21204553351245 has 64 divisors (see below), whose sum is σ = 37075798545408. Its totient is φ = 10263163904000.

The previous prime is 21204553351217. The next prime is 21204553351337. The reversal of 21204553351245 is 54215335540212.

It is not a de Polignac number, because 21204553351245 - 2³¹ = 21202405867597 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21204553351197 and 21204553351206.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 762657514 + ... + 762685316.

It is an arithmetic number, because the mean of its divisors is an integer number (579309352272).

Almost surely, 2^{21204553351245} is an apocalyptic number.

It is an amenable number.

21204553351245 is a deficient number, since it is larger than the sum of its proper divisors (15871245194163).

21204553351245 is a wasteful number, since it uses less digits than its factorization.

21204553351245 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35674.

The product of its (nonzero) digits is 720000, while the sum is 42.

Adding to 21204553351245 its reverse (54215335540212), we get a palindrome (75419888891457).

The spelling of 21204553351245 in words is "twenty-one trillion, two hundred four billion, five hundred fifty-three million, three hundred fifty-one thousand, two hundred forty-five".