21601123 has 4 divisors (see below), whose sum is σ = 21650328. Its totient is φ = 21551920.

The previous prime is 21601121. The next prime is 21601171. The reversal of 21601123 is 32110612.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21601123 - 2¹ = 21601121 is a prime.

It is a super-2 number, since 2×21601123² = 933217029722258, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21601097 and 21601106.

It is not an unprimeable number, because it can be changed into a prime (21601121) 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, 23938 + ... + 24823.

It is an arithmetic number, because the mean of its divisors is an integer number (5412582).

Almost surely, 2^21601123 is an apocalyptic number.

21601123 is a deficient number, since it is larger than the sum of its proper divisors (49205).

21601123 is an equidigital number, since it uses as much as digits as its factorization.

21601123 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 49204.

The product of its (nonzero) digits is 72, while the sum is 16.

The square root of 21601123 is about 4647.7008294424. The cubic root of 21601123 is about 278.5001563260.

Adding to 21601123 its reverse (32110612), we get a palindrome (53711735).

The spelling of 21601123 in words is "twenty-one million, six hundred one thousand, one hundred twenty-three".