21312170 has 32 divisors (see below), whose sum is σ = 42050880. Its totient is φ = 7712640.

The previous prime is 21312163. The next prime is 21312173. The reversal of 21312170 is 7121312.

It is not an unprimeable number, because it can be changed into a prime (21312173) 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 15 ways as a sum of consecutive naturals, for example, 34121 + ... + 34739.

It is an arithmetic number, because the mean of its divisors is an integer number (1314090).

Almost surely, 2^21312170 is an apocalyptic number.

21312170 is a deficient number, since it is larger than the sum of its proper divisors (20738710).

21312170 is a wasteful number, since it uses less digits than its factorization.

21312170 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 950.

The product of its (nonzero) digits is 84, while the sum is 17.

The square root of 21312170 is about 4616.5105870127. The cubic root of 21312170 is about 277.2527679231.

Adding to 21312170 its reverse (7121312), we get a palindrome (28433482).

The spelling of 21312170 in words is "twenty-one million, three hundred twelve thousand, one hundred seventy".