21662361 has 18 divisors (see below), whose sum is σ = 36399402. Its totient is φ = 12378240.

The previous prime is 21662359. The next prime is 21662363. The reversal of 21662361 is 16326612.

It is an interprime number because it is at equal distance from previous prime (21662359) and next prime (21662363).

It can be written as a sum of positive squares in only one way, i.e., 13505625 + 8156736 = 3675^2 + 2856^2 .

It is not a de Polignac number, because 21662361 - 2¹ = 21662359 is a prime.

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (21662363) by changing a digit.

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 17 ways as a sum of consecutive naturals, for example, 24120 + ... + 25001.

It is an arithmetic number, because the mean of its divisors is an integer number (2022189).

Almost surely, 2^21662361 is an apocalyptic number.

21662361 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21662361 is a deficient number, since it is larger than the sum of its proper divisors (14737041).

21662361 is a wasteful number, since it uses less digits than its factorization.

21662361 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 49141 (or 49131 counting only the distinct ones).

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

The square root of 21662361 is about 4654.2841554851. The cubic root of 21662361 is about 278.7630855795.

Adding to 21662361 its reverse (16326612), we get a palindrome (37988973).

The spelling of 21662361 in words is "twenty-one million, six hundred sixty-two thousand, three hundred sixty-one".