21267985 has 16 divisors (see below), whose sum is σ = 26979840. Its totient is φ = 16061760.

The previous prime is 21267941. The next prime is 21267989. The reversal of 21267985 is 58976212.

It is a de Polignac number, because none of the positive numbers 2^k-21267985 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21267989) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 7915 + ... + 10255.

It is an arithmetic number, because the mean of its divisors is an integer number (1686240).

Almost surely, 2^21267985 is an apocalyptic number.

It is an amenable number.

21267985 is a deficient number, since it is larger than the sum of its proper divisors (5711855).

21267985 is a wasteful number, since it uses less digits than its factorization.

21267985 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2448.

The product of its digits is 60480, while the sum is 40.

The square root of 21267985 is about 4611.7225632078. The cubic root of 21267985 is about 277.0610325706.

The spelling of 21267985 in words is "twenty-one million, two hundred sixty-seven thousand, nine hundred eighty-five".