21013667 has 4 divisors (see below), whose sum is σ = 21085680. Its totient is φ = 20941656.

The previous prime is 21013633. The next prime is 21013709. The reversal of 21013667 is 76631012.

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 21013667 - 2²⁰ = 19965091 is a prime.

It is a super-3 number, since 3×21013667³ (a number of 23 digits) contains 333 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21018667) 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, 35567 + ... + 36152.

It is an arithmetic number, because the mean of its divisors is an integer number (5271420).

Almost surely, 2^21013667 is an apocalyptic number.

21013667 is a deficient number, since it is larger than the sum of its proper divisors (72013).

21013667 is an equidigital number, since it uses as much as digits as its factorization.

21013667 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 72012.

The product of its (nonzero) digits is 1512, while the sum is 26.

The square root of 21013667 is about 4584.0666443672. The cubic root of 21013667 is about 275.9522557966.

Adding to 21013667 its reverse (76631012), we get a palindrome (97644679).

The spelling of 21013667 in words is "twenty-one million, thirteen thousand, six hundred sixty-seven".