21361550 has 36 divisors (see below), whose sum is σ = 46224720. Its totient is φ = 7323120.

The previous prime is 21361519. The next prime is 21361579. The reversal of 21361550 is 5516312.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 1910 + ... + 6809.

It is an arithmetic number, because the mean of its divisors is an integer number (1284020).

Almost surely, 2^21361550 is an apocalyptic number.

21361550 is an abundant number, since it is smaller than the sum of its proper divisors (24863170).

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

21361550 is a wasteful number, since it uses less digits than its factorization.

21361550 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8745 (or 8733 counting only the distinct ones).

The product of its (nonzero) digits is 900, while the sum is 23.

The square root of 21361550 is about 4621.8556879245. The cubic root of 21361550 is about 277.4667330194.

Adding to 21361550 its reverse (5516312), we get a palindrome (26877862).

The spelling of 21361550 in words is "twenty-one million, three hundred sixty-one thousand, five hundred fifty".