21155235201253 has 8 divisors (see below), whose sum is σ = 21359291821560. Its totient is φ = 20951359888320.

The previous prime is 21155235201209. The next prime is 21155235201299. The reversal of 21155235201253 is 35210253255112.

It can be written as a sum of positive squares in 4 ways, for example, as 11528754741604 + 9626480459649 = 3395402^2 + 3102657^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21155235201253 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 (21155235201053) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 45092350 + ... + 45559087.

It is an arithmetic number, because the mean of its divisors is an integer number (2669911477695).

Almost surely, 2^{21155235201253} is an apocalyptic number.

It is an amenable number.

21155235201253 is a deficient number, since it is larger than the sum of its proper divisors (204056620307).

21155235201253 is a wasteful number, since it uses less digits than its factorization.

21155235201253 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 90653687.

The product of its (nonzero) digits is 90000, while the sum is 37.

Adding to 21155235201253 its reverse (35210253255112), we get a palindrome (56365488456365).

The spelling of 21155235201253 in words is "twenty-one trillion, one hundred fifty-five billion, two hundred thirty-five million, two hundred one thousand, two hundred fifty-three".