21699967 has 4 divisors (see below), whose sum is σ = 21923776. Its totient is φ = 21476160.

The previous prime is 21699901. The next prime is 21700001. The reversal of 21699967 is 76999612.

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 21699967 - 2¹⁵ = 21667199 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21699967.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21690967) 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, 111759 + ... + 111952.

It is an arithmetic number, because the mean of its divisors is an integer number (5480944).

Almost surely, 2^21699967 is an apocalyptic number.

21699967 is a deficient number, since it is larger than the sum of its proper divisors (223809).

21699967 is an equidigital number, since it uses as much as digits as its factorization.

21699967 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 223808.

The product of its digits is 367416, while the sum is 49.

The square root of 21699967 is about 4658.3223374945. The cubic root of 21699967 is about 278.9243038352.

The spelling of 21699967 in words is "twenty-one million, six hundred ninety-nine thousand, nine hundred sixty-seven".