21000455361 has 18 divisors (see below), whose sum is σ = 31499092482. Its totient is φ = 14000299200.

The previous prime is 21000455341. The next prime is 21000455363. The reversal of 21000455361 is 16355400012.

21000455361 is a `hidden beast` number, since 2 + 100 + 0 + 4 + 553 + 6 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 20671250625 + 329204736 = 143775^2 + 18144^2 .

It is not a de Polignac number, because 21000455361 - 2²⁷ = 20866237633 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (21000455363) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 1593840 + ... + 1606961.

Almost surely, 2^21000455361 is an apocalyptic number.

It is an amenable number.

21000455361 is a deficient number, since it is larger than the sum of its proper divisors (10498637121).

21000455361 is an frugal number, since it uses more digits than its factorization.

21000455361 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3200825 (or 3200804 counting only the distinct ones).

The product of its (nonzero) digits is 3600, while the sum is 27.

Adding to 21000455361 its reverse (16355400012), we get a palindrome (37355855373).

The spelling of 21000455361 in words is "twenty-one billion, four hundred fifty-five thousand, three hundred sixty-one".