21072985 has 8 divisors (see below), whose sum is σ = 25312320. Its totient is φ = 16841904.

The previous prime is 21072973. The next prime is 21073001. The reversal of 21072985 is 58927012.

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 21072985 - 2¹¹ = 21070937 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a self number, because there is not a number n which added to its sum of digits gives 21072985.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8274 + ... + 10516.

It is an arithmetic number, because the mean of its divisors is an integer number (3164040).

Almost surely, 2^21072985 is an apocalyptic number.

It is an amenable number.

21072985 is a deficient number, since it is larger than the sum of its proper divisors (4239335).

21072985 is a wasteful number, since it uses less digits than its factorization.

21072985 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4127.

The product of its (nonzero) digits is 10080, while the sum is 34.

The square root of 21072985 is about 4590.5321042337. The cubic root of 21072985 is about 276.2116672513.

Adding to 21072985 its reverse (58927012), we get a palindrome (79999997).

The spelling of 21072985 in words is "twenty-one million, seventy-two thousand, nine hundred eighty-five".