21621415563553 has 16 divisors (see below), whose sum is σ = 24525302518080. Its totient is φ = 18896074127424.

The previous prime is 21621415563523. The next prime is 21621415563557. The reversal of 21621415563553 is 35536551412612.

It is a de Polignac number, because none of the positive numbers 2^k-21621415563553 is a prime.

It is a super-2 number, since 2×21621415563553² (a number of 27 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21621415563497 and 21621415563506.

It is not an unprimeable number, because it can be changed into a prime (21621415563557) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 26736151 + ... + 27532972.

It is an arithmetic number, because the mean of its divisors is an integer number (1532831407380).

Almost surely, 2^{21621415563553} is an apocalyptic number.

It is an amenable number.

21621415563553 is a deficient number, since it is larger than the sum of its proper divisors (2903886954527).

21621415563553 is a wasteful number, since it uses less digits than its factorization.

21621415563553 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 54270768.

The product of its digits is 3240000, while the sum is 49.

The spelling of 21621415563553 in words is "twenty-one trillion, six hundred twenty-one billion, four hundred fifteen million, five hundred sixty-three thousand, five hundred fifty-three".