21123371 has 4 divisors (see below), whose sum is σ = 21203952. Its totient is φ = 21042792.

The previous prime is 21123359. The next prime is 21123373. The reversal of 21123371 is 17332112.

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 21123371 - 2²² = 16929067 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21123373) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 39896 + ... + 40421.

It is an arithmetic number, because the mean of its divisors is an integer number (5300988).

Almost surely, 2^21123371 is an apocalyptic number.

21123371 is a deficient number, since it is larger than the sum of its proper divisors (80581).

21123371 is an equidigital number, since it uses as much as digits as its factorization.

21123371 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 80580.

The product of its digits is 252, while the sum is 20.

The square root of 21123371 is about 4596.0168624582. The cubic root of 21123371 is about 276.4316348806.

Adding to 21123371 its reverse (17332112), we get a palindrome (38455483).

The spelling of 21123371 in words is "twenty-one million, one hundred twenty-three thousand, three hundred seventy-one".