21253967 has 4 divisors (see below), whose sum is σ = 24290256. Its totient is φ = 18217680.

The previous prime is 21253963. The next prime is 21253979. The reversal of 21253967 is 76935212.

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 21253967 - 2² = 21253963 is a prime.

It is a super-2 number, since 2×21253967² = 903462226474178, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21253963) 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, 1518134 + ... + 1518147.

It is an arithmetic number, because the mean of its divisors is an integer number (6072564).

Almost surely, 2^21253967 is an apocalyptic number.

21253967 is a deficient number, since it is larger than the sum of its proper divisors (3036289).

21253967 is an equidigital number, since it uses as much as digits as its factorization.

21253967 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3036288.

The product of its digits is 22680, while the sum is 35.

The square root of 21253967 is about 4610.2024901299. The cubic root of 21253967 is about 277.0001477059. Note that the first 3 decimals are identical.

The spelling of 21253967 in words is "twenty-one million, two hundred fifty-three thousand, nine hundred sixty-seven".