21008716 has 6 divisors (see below), whose sum is σ = 36765260. Its totient is φ = 10504356.

The previous prime is 21008681. The next prime is 21008749. The reversal of 21008716 is 61780012.

It is a super-2 number, since 2×21008716² = 882732295937312, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2626086 + ... + 2626093.

Almost surely, 2^21008716 is an apocalyptic number.

It is an amenable number.

21008716 is a deficient number, since it is larger than the sum of its proper divisors (15756544).

21008716 is a wasteful number, since it uses less digits than its factorization.

21008716 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5252183 (or 5252181 counting only the distinct ones).

The product of its (nonzero) digits is 672, while the sum is 25.

The square root of 21008716 is about 4583.5265898651. The cubic root of 21008716 is about 275.9305818556.

Adding to 21008716 its reverse (61780012), we get a palindrome (82788728).

It can be divided in two parts, 2100 and 8716, that added together give a square (10816 = 104²).

The spelling of 21008716 in words is "twenty-one million, eight thousand, seven hundred sixteen".