21123401 has 8 divisors (see below), whose sum is σ = 24086664. Its totient is φ = 18351360.

The previous prime is 21123391. The next prime is 21123457. The reversal of 21123401 is 10432112.

It can be written as a sum of positive squares in 4 ways, for example, as 8880400 + 12243001 = 2980^2 + 3499^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21123401 - 2¹⁴ = 21107017 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 (21123461) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 47570 + ... + 48011.

It is an arithmetic number, because the mean of its divisors is an integer number (3010833).

Almost surely, 2^21123401 is an apocalyptic number.

It is an amenable number.

21123401 is a deficient number, since it is larger than the sum of its proper divisors (2963263).

21123401 is a wasteful number, since it uses less digits than its factorization.

21123401 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 95611.

The product of its (nonzero) digits is 48, while the sum is 14.

The square root of 21123401 is about 4596.0201261526. The cubic root of 21123401 is about 276.4317657459.

Adding to 21123401 its reverse (10432112), we get a palindrome (31555513).

The spelling of 21123401 in words is "twenty-one million, one hundred twenty-three thousand, four hundred one".