21393967 has 8 divisors (see below), whose sum is σ = 25293600. Its totient is φ = 17705184.

The previous prime is 21393961. The next prime is 21393989. The reversal of 21393967 is 76939312.

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

It is not a de Polignac number, because 21393967 - 2³ = 21393959 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21393961) 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 7 ways as a sum of consecutive naturals, for example, 52492 + ... + 52897.

It is an arithmetic number, because the mean of its divisors is an integer number (3161700).

Almost surely, 2^21393967 is an apocalyptic number.

21393967 is a deficient number, since it is larger than the sum of its proper divisors (3899633).

21393967 is a wasteful number, since it uses less digits than its factorization.

21393967 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 105425.

The product of its digits is 61236, while the sum is 40.

The square root of 21393967 is about 4625.3612831864. The cubic root of 21393967 is about 277.6070176742.

The spelling of 21393967 in words is "twenty-one million, three hundred ninety-three thousand, nine hundred sixty-seven".