21601616 has 10 divisors (see below), whose sum is σ = 41853162. Its totient is φ = 10800800.

The previous prime is 21601603. The next prime is 21601627. The reversal of 21601616 is 61610612.

It can be written as a sum of positive squares in only one way, i.e., 16032016 + 5569600 = 4004^2 + 2360^2 .

It is a super-2 number, since 2×21601616² = 933259627622912, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21601591 and 21601600.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 675035 + ... + 675066.

Almost surely, 2^21601616 is an apocalyptic number.

It is an amenable number.

21601616 is a deficient number, since it is larger than the sum of its proper divisors (20251546).

21601616 is a wasteful number, since it uses less digits than its factorization.

21601616 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1350109 (or 1350103 counting only the distinct ones).

The product of its (nonzero) digits is 432, while the sum is 23.

The square root of 21601616 is about 4647.7538661164. The cubic root of 21601616 is about 278.5022750358.

The spelling of 21601616 in words is "twenty-one million, six hundred one thousand, six hundred sixteen".