21661362 has 18 divisors (see below), whose sum is σ = 46975773. Its totient is φ = 7213872.

The previous prime is 21661357. The next prime is 21661397. The reversal of 21661362 is 26316612.

It can be written as a sum of positive squares in 2 ways, for example, as 20602521 + 1058841 = 4539^2 + 1029^2 .

It is a tau number, because it is divible by the number of its divisors (18).

It is an ABA number since it can be written as A⋅B^A, here for A=2, B=3291.

It is a nude number because it is divisible by every one of its digits.

It is a plaindrome in base 11.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 19198 + ... + 20294.

Almost surely, 2^21661362 is an apocalyptic number.

21661362 is an abundant number, since it is smaller than the sum of its proper divisors (25314411).

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

21661362 is an equidigital number, since it uses as much as digits as its factorization.

21661362 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2202 (or 1102 counting only the distinct ones).

The product of its digits is 2592, while the sum is 27.

The square root of 21661362 is about 4654.1768337699. The cubic root of 21661362 is about 278.7588002879.

Multiplying 21661362 by its product of digits (2592), we get a square (56146250304 = 236952²).

Adding to 21661362 its reverse (26316612), we get a palindrome (47977974).

The spelling of 21661362 in words is "twenty-one million, six hundred sixty-one thousand, three hundred sixty-two".