21361000 has 64 divisors (see below), whose sum is σ = 51302160. Its totient is φ = 8320000.

The previous prime is 21360971. The next prime is 21361001. The reversal of 21361000 is 16312.

It can be written as a sum of positive squares in 8 ways, for example, as 948676 + 20412324 = 974^2 + 4518^2 .

It is not an unprimeable number, because it can be changed into a prime (21361001) 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, 40740 + ... + 41260.

Almost surely, 2^21361000 is an apocalyptic number.

21361000 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21361000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25651080).

21361000 is an abundant number, since it is smaller than the sum of its proper divisors (29941160).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21361000 is a wasteful number, since it uses less digits than its factorization.

21361000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 583 (or 569 counting only the distinct ones).

The product of its (nonzero) digits is 36, while the sum is 13.

The square root of 21361000 is about 4621.7961876310. The cubic root of 21361000 is about 277.4643516689.

Adding to 21361000 its reverse (16312), we get a palindrome (21377312).

It can be divided in two parts, 2136 and 1000, that added together give a square (3136 = 56²).

The spelling of 21361000 in words is "twenty-one million, three hundred sixty-one thousand".