21999005 has 16 divisors (see below), whose sum is σ = 30290304. Its totient is φ = 15024960.

The previous prime is 21998993. The next prime is 21999007. The reversal of 21999005 is 50099912.

It is not a de Polignac number, because 21999005 - 2⁴ = 21998989 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (35).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21999007) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8795 + ... + 11015.

It is an arithmetic number, because the mean of its divisors is an integer number (1893144).

Almost surely, 2^21999005 is an apocalyptic number.

It is an amenable number.

21999005 is a deficient number, since it is larger than the sum of its proper divisors (8291299).

21999005 is a wasteful number, since it uses less digits than its factorization.

21999005 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2516.

The product of its (nonzero) digits is 7290, while the sum is 35.

The square root of 21999005 is about 4690.3096912677. The cubic root of 21999005 is about 280.1997087153.

The spelling of 21999005 in words is "twenty-one million, nine hundred ninety-nine thousand, five".