21994229 has 4 divisors (see below), whose sum is σ = 23151840. Its totient is φ = 20836620.

The previous prime is 21994213. The next prime is 21994237. The reversal of 21994229 is 92249912.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21994229 - 2⁴ = 21994213 is a prime.

It is a super-2 number, since 2×21994229² = 967492218608882, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21994192 and 21994201.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21994529) 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, 578777 + ... + 578814.

It is an arithmetic number, because the mean of its divisors is an integer number (5787960).

Almost surely, 2^21994229 is an apocalyptic number.

It is an amenable number.

21994229 is a deficient number, since it is larger than the sum of its proper divisors (1157611).

21994229 is a wasteful number, since it uses less digits than its factorization.

21994229 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1157610.

The product of its digits is 23328, while the sum is 38.

The square root of 21994229 is about 4689.8005288072. The cubic root of 21994229 is about 280.1794300608.

The spelling of 21994229 in words is "twenty-one million, nine hundred ninety-four thousand, two hundred twenty-nine".