21971213 has 8 divisors (see below), whose sum is σ = 24092640. Its totient is φ = 19870480.

The previous prime is 21971197. The next prime is 21971221. The reversal of 21971213 is 31217912.

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

It is a cyclic number.

It is not a de Polignac number, because 21971213 - 2⁴ = 21971197 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21971263) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2903 + ... + 7236.

It is an arithmetic number, because the mean of its divisors is an integer number (3011580).

Almost surely, 2^21971213 is an apocalyptic number.

It is an amenable number.

21971213 is a deficient number, since it is larger than the sum of its proper divisors (2121427).

21971213 is a wasteful number, since it uses less digits than its factorization.

21971213 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10347.

The product of its digits is 756, while the sum is 26.

The square root of 21971213 is about 4687.3460508053. The cubic root of 21971213 is about 280.0816641049.

The spelling of 21971213 in words is "twenty-one million, nine hundred seventy-one thousand, two hundred thirteen".