21208965 has 8 divisors (see below), whose sum is σ = 33934368. Its totient is φ = 11311440.

The previous prime is 21208961. The next prime is 21208969. The reversal of 21208965 is 56980212.

It is an interprime number because it is at equal distance from previous prime (21208961) and next prime (21208969).

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

It is not a de Polignac number, because 21208965 - 2² = 21208961 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21208961) 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 7 ways as a sum of consecutive naturals, for example, 706951 + ... + 706980.

It is an arithmetic number, because the mean of its divisors is an integer number (4241796).

Almost surely, 2^21208965 is an apocalyptic number.

It is an amenable number.

21208965 is a deficient number, since it is larger than the sum of its proper divisors (12725403).

21208965 is a wasteful number, since it uses less digits than its factorization.

21208965 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1413939.

The product of its (nonzero) digits is 8640, while the sum is 33.

The square root of 21208965 is about 4605.3192071777. The cubic root of 21208965 is about 276.8045078523.

The spelling of 21208965 in words is "twenty-one million, two hundred eight thousand, nine hundred sixty-five".