21967399 has 4 divisors (see below), whose sum is σ = 22185000. Its totient is φ = 21749800.

The previous prime is 21967397. The next prime is 21967403. The reversal of 21967399 is 99376912.

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 21967399 - 2¹ = 21967397 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 (21967397) 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, 108649 + ... + 108850.

It is an arithmetic number, because the mean of its divisors is an integer number (5546250).

Almost surely, 2^21967399 is an apocalyptic number.

21967399 is a deficient number, since it is larger than the sum of its proper divisors (217601).

21967399 is a wasteful number, since it uses less digits than its factorization.

21967399 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 217600.

The product of its digits is 183708, while the sum is 46.

The square root of 21967399 is about 4686.9391931195. The cubic root of 21967399 is about 280.0654566355.

It can be divided in two parts, 21967 and 399, that added together give a triangular number (22366 = T₂₁₁).

The spelling of 21967399 in words is "twenty-one million, nine hundred sixty-seven thousand, three hundred ninety-nine".