21115502501553 has 6 divisors (see below), whose sum is σ = 30500170280034. Its totient is φ = 14077001667696.

The previous prime is 21115502501539. The next prime is 21115502501567. The reversal of 21115502501553 is 35510520551112.

21115502501553 is a `hidden beast` number, since 2 + 1 + 1 + 1 + 5 + 50 + 2 + 50 + 1 + 553 = 666.

It is an interprime number because it is at equal distance from previous prime (21115502501539) and next prime (21115502501567).

It can be written as a sum of positive squares in only one way, i.e., 19456012344609 + 1659490156944 = 4410897^2 + 1288212^2 .

It is not a de Polignac number, because 21115502501553 - 2¹⁴ = 21115502485169 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21115502501953) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1173083472300 + ... + 1173083472317.

It is an arithmetic number, because the mean of its divisors is an integer number (5083361713339).

Almost surely, 2^{21115502501553} is an apocalyptic number.

It is an amenable number.

21115502501553 is a deficient number, since it is larger than the sum of its proper divisors (9384667778481).

21115502501553 is a wasteful number, since it uses less digits than its factorization.

21115502501553 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2346166944623 (or 2346166944620 counting only the distinct ones).

The product of its (nonzero) digits is 37500, while the sum is 36.

The spelling of 21115502501553 in words is "twenty-one trillion, one hundred fifteen billion, five hundred two million, five hundred one thousand, five hundred fifty-three".