21081652 has 6 divisors (see below), whose sum is σ = 36892898. Its totient is φ = 10540824.

The previous prime is 21081647. The next prime is 21081673. The reversal of 21081652 is 25618012.

It can be written as a sum of positive squares in only one way, i.e., 17255716 + 3825936 = 4154^2 + 1956^2 .

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, 2635203 + ... + 2635210.

Almost surely, 2^21081652 is an apocalyptic number.

It is an amenable number.

21081652 is a deficient number, since it is larger than the sum of its proper divisors (15811246).

21081652 is a wasteful number, since it uses less digits than its factorization.

21081652 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5270417 (or 5270415 counting only the distinct ones).

The product of its (nonzero) digits is 960, while the sum is 25.

The square root of 21081652 is about 4591.4760154007. The cubic root of 21081652 is about 276.2495292881.

Adding to 21081652 its reverse (25618012), we get a palindrome (46699664).

The spelling of 21081652 in words is "twenty-one million, eighty-one thousand, six hundred fifty-two".