21120687 has 12 divisors (see below), whose sum is σ = 34866000. Its totient is φ = 12068928.

The previous prime is 21120677. The next prime is 21120689. The reversal of 21120687 is 78602112.

It is not a de Polignac number, because 21120687 - 2⁷ = 21120559 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21120687.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21120689) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 167562 + ... + 167687.

It is an arithmetic number, because the mean of its divisors is an integer number (2905500).

Almost surely, 2^21120687 is an apocalyptic number.

21120687 is a deficient number, since it is larger than the sum of its proper divisors (13745313).

21120687 is a wasteful number, since it uses less digits than its factorization.

21120687 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 335262 (or 335259 counting only the distinct ones).

The product of its (nonzero) digits is 1344, while the sum is 27.

The square root of 21120687 is about 4595.7248612161. The cubic root of 21120687 is about 276.4199263023.

Adding to 21120687 its reverse (78602112), we get a palindrome (99722799).

The spelling of 21120687 in words is "twenty-one million, one hundred twenty thousand, six hundred eighty-seven".