21087268 has 6 divisors (see below), whose sum is σ = 36902726. Its totient is φ = 10543632.

The previous prime is 21087221. The next prime is 21087277. The reversal of 21087268 is 86278012.

It can be written as a sum of positive squares in only one way, i.e., 10705984 + 10381284 = 3272^2 + 3222^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2635905 + ... + 2635912.

Almost surely, 2^21087268 is an apocalyptic number.

It is an amenable number.

21087268 is a deficient number, since it is larger than the sum of its proper divisors (15815458).

21087268 is a wasteful number, since it uses less digits than its factorization.

21087268 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5271821 (or 5271819 counting only the distinct ones).

The product of its (nonzero) digits is 10752, while the sum is 34.

The square root of 21087268 is about 4592.0875427195. The cubic root of 21087268 is about 276.2740574041.

It can be divided in two parts, 210 and 87268, that added together give a palindrome (87478).

The spelling of 21087268 in words is "twenty-one million, eighty-seven thousand, two hundred sixty-eight".