21020716 has 6 divisors (see below), whose sum is σ = 36786260. Its totient is φ = 10510356.

The previous prime is 21020683. The next prime is 21020719. The reversal of 21020716 is 61702012.

It is a junction number, because it is equal to n+sod(n) for n = 21020693 and 21020702.

It is not an unprimeable number, because it can be changed into a prime (21020719) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2627586 + ... + 2627593.

Almost surely, 2^21020716 is an apocalyptic number.

It is an amenable number.

21020716 is a deficient number, since it is larger than the sum of its proper divisors (15765544).

21020716 is a wasteful number, since it uses less digits than its factorization.

21020716 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5255183 (or 5255181 counting only the distinct ones).

The product of its (nonzero) digits is 168, while the sum is 19.

The square root of 21020716 is about 4584.8354387044. The cubic root of 21020716 is about 275.9831082570.

Adding to 21020716 its reverse (61702012), we get a palindrome (82722728).

It can be divided in two parts, 21020 and 716, that added together give a triangular number (21736 = T₂₀₈).

The spelling of 21020716 in words is "twenty-one million, twenty thousand, seven hundred sixteen".