21151716 has 24 divisors (see below), whose sum is σ = 50688960. Its totient is φ = 6859872.

The previous prime is 21151687. The next prime is 21151721. The reversal of 21151716 is 61715112.

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, 23376 + ... + 24263.

It is an arithmetic number, because the mean of its divisors is an integer number (2112040).

Almost surely, 2^21151716 is an apocalyptic number.

It is an amenable number.

21151716 is an abundant number, since it is smaller than the sum of its proper divisors (29537244).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21151716 is a wasteful number, since it uses less digits than its factorization.

21151716 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 47683 (or 47681 counting only the distinct ones).

The product of its digits is 420, while the sum is 24.

The square root of 21151716 is about 4599.0994770716. The cubic root of 21151716 is about 276.5552255165. Note that the first 3 decimals are identical.

Adding to 21151716 its reverse (61715112), we get a palindrome (82866828).

The spelling of 21151716 in words is "twenty-one million, one hundred fifty-one thousand, seven hundred sixteen".