21613623 has 16 divisors (see below), whose sum is σ = 29402880. Its totient is φ = 14120064.

The previous prime is 21613619. The next prime is 21613639. The reversal of 21613623 is 32631612.

It is a happy number.

It is not a de Polignac number, because 21613623 - 2² = 21613619 is a prime.

It is a super-2 number, since 2×21613623² = 934297398372258, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21613593 and 21613602.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21613663) 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 15 ways as a sum of consecutive naturals, for example, 34608 + ... + 35226.

It is an arithmetic number, because the mean of its divisors is an integer number (1837680).

Almost surely, 2^21613623 is an apocalyptic number.

21613623 is a deficient number, since it is larger than the sum of its proper divisors (7789257).

21613623 is a wasteful number, since it uses less digits than its factorization.

21613623 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 838.

The product of its digits is 1296, while the sum is 24.

The square root of 21613623 is about 4649.0453858830. The cubic root of 21613623 is about 278.5538661982.

The spelling of 21613623 in words is "twenty-one million, six hundred thirteen thousand, six hundred twenty-three".