21357211 has 4 divisors (see below), whose sum is σ = 21511000. Its totient is φ = 21203424.

The previous prime is 21357199. The next prime is 21357247. The reversal of 21357211 is 11275312.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21357211 - 2¹¹ = 21355163 is a prime.

It is a super-2 number, since 2×21357211² = 912260923397042, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21357911) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 76686 + ... + 76963.

It is an arithmetic number, because the mean of its divisors is an integer number (5377750).

Almost surely, 2^21357211 is an apocalyptic number.

21357211 is a deficient number, since it is larger than the sum of its proper divisors (153789).

21357211 is a wasteful number, since it uses less digits than its factorization.

21357211 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 153788.

The product of its digits is 420, while the sum is 22.

The square root of 21357211 is about 4621.3862638823. The cubic root of 21357211 is about 277.4479452179.

The spelling of 21357211 in words is "twenty-one million, three hundred fifty-seven thousand, two hundred eleven".