21212279 has 8 divisors (see below), whose sum is σ = 24147072. Its totient is φ = 18445240.

The previous prime is 21212273. The next prime is 21212281. The reversal of 21212279 is 97221212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21212279 - 2⁴ = 21212263 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21212273) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 41669 + ... + 42174.

It is an arithmetic number, because the mean of its divisors is an integer number (3018384).

Almost surely, 2^21212279 is an apocalyptic number.

21212279 is a deficient number, since it is larger than the sum of its proper divisors (2934793).

21212279 is a wasteful number, since it uses less digits than its factorization.

21212279 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 83877.

The product of its digits is 1008, while the sum is 26.

The square root of 21212279 is about 4605.6789944589. The cubic root of 21212279 is about 276.8189244345.

The spelling of 21212279 in words is "twenty-one million, two hundred twelve thousand, two hundred seventy-nine".