21771229 has 4 divisors (see below), whose sum is σ = 21942784. Its totient is φ = 21599676.

The previous prime is 21771221. The next prime is 21771247. The reversal of 21771229 is 92217712.

It is a happy number.

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 21771229 - 2³ = 21771221 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 21771229.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21771221) 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, 85587 + ... + 85840.

It is an arithmetic number, because the mean of its divisors is an integer number (5485696).

Almost surely, 2^21771229 is an apocalyptic number.

It is an amenable number.

21771229 is a deficient number, since it is larger than the sum of its proper divisors (171555).

21771229 is a wasteful number, since it uses less digits than its factorization.

21771229 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 171554.

The product of its digits is 3528, while the sum is 31.

The square root of 21771229 is about 4665.9649591483. The cubic root of 21771229 is about 279.2292963911.

The spelling of 21771229 in words is "twenty-one million, seven hundred seventy-one thousand, two hundred twenty-nine".