21624361 has 4 divisors (see below), whose sum is σ = 23590224. Its totient is φ = 19658500.

The previous prime is 21624359. The next prime is 21624367. The reversal of 21624361 is 16342612.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21624361 - 2¹ = 21624359 is a prime.

It is a super-2 number, since 2×21624361² = 935225977316642, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21624367) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 982915 + ... + 982936.

It is an arithmetic number, because the mean of its divisors is an integer number (5897556).

Almost surely, 2^21624361 is an apocalyptic number.

It is an amenable number.

21624361 is a deficient number, since it is larger than the sum of its proper divisors (1965863).

21624361 is a wasteful number, since it uses less digits than its factorization.

21624361 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1965862.

The product of its digits is 1728, while the sum is 25.

The square root of 21624361 is about 4650.2001032214. The cubic root of 21624361 is about 278.5999885937.

Adding to 21624361 its reverse (16342612), we get a palindrome (37966973).

The spelling of 21624361 in words is "twenty-one million, six hundred twenty-four thousand, three hundred sixty-one".