21942599 has 16 divisors (see below), whose sum is σ = 25850880. Its totient is φ = 18234720.

The previous prime is 21942581. The next prime is 21942601. The reversal of 21942599 is 99524912.

It is a happy number.

It is not a de Polignac number, because 21942599 - 2²⁰ = 20894023 is a prime.

It is a Smith number, since the sum of its digits (41) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21942509) 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 15 ways as a sum of consecutive naturals, for example, 80834 + ... + 81104.

It is an arithmetic number, because the mean of its divisors is an integer number (1615680).

Almost surely, 2^21942599 is an apocalyptic number.

21942599 is a deficient number, since it is larger than the sum of its proper divisors (3908281).

21942599 is a wasteful number, since it uses less digits than its factorization.

21942599 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 590.

The product of its digits is 58320, while the sum is 41.

The square root of 21942599 is about 4684.2927961433. The cubic root of 21942599 is about 279.9600240548.

The spelling of 21942599 in words is "twenty-one million, nine hundred forty-two thousand, five hundred ninety-nine".