21071616 has 36 divisors (see below), whose sum is σ = 56083272. Its totient is φ = 7023616.

The previous prime is 21071587. The next prime is 21071621. The reversal of 21071616 is 61617012.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a congruent number.

It is an unprimeable number.

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 in 3 ways as a sum of consecutive naturals, for example, 12951 + ... + 14486.

Almost surely, 2^21071616 is an apocalyptic number.

It is an amenable number.

21071616 is an abundant number, since it is smaller than the sum of its proper divisors (35011656).

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

21071616 is an equidigital number, since it uses as much as digits as its factorization.

21071616 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27456 (or 27442 counting only the distinct ones).

The product of its (nonzero) digits is 504, while the sum is 24.

The square root of 21071616 is about 4590.3829905575. The cubic root of 21071616 is about 276.2056857864.

Adding to 21071616 its reverse (61617012), we get a palindrome (82688628).

The spelling of 21071616 in words is "twenty-one million, seventy-one thousand, six hundred sixteen".