21613361 has 12 divisors (see below), whose sum is σ = 27428400. Its totient is φ = 16841160.

The previous prime is 21613349. The next prime is 21613367. The reversal of 21613361 is 16331612.

It is a happy number.

It is not a de Polignac number, because 21613361 - 2¹⁸ = 21351217 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21613367) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 19511 + ... + 20588.

It is an arithmetic number, because the mean of its divisors is an integer number (2285700).

Almost surely, 2^21613361 is an apocalyptic number.

It is an amenable number.

21613361 is a deficient number, since it is larger than the sum of its proper divisors (5815039).

21613361 is a wasteful number, since it uses less digits than its factorization.

21613361 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40124 (or 40117 counting only the distinct ones).

The product of its digits is 648, while the sum is 23.

The square root of 21613361 is about 4649.0172079699. The cubic root of 21613361 is about 278.5527406517.

Adding to 21613361 its reverse (16331612), we get a palindrome (37944973).

The spelling of 21613361 in words is "twenty-one million, six hundred thirteen thousand, three hundred sixty-one".