21661652 has 12 divisors (see below), whose sum is σ = 38299380. Its totient is φ = 10718976.

The previous prime is 21661643. The next prime is 21661657. The reversal of 21661652 is 25616612.

It can be written as a sum of positive squares in 2 ways, for example, as 9523396 + 12138256 = 3086^2 + 3484^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21661657) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 27527 + ... + 28302.

It is an arithmetic number, because the mean of its divisors is an integer number (3191615).

Almost surely, 2^21661652 is an apocalyptic number.

It is an amenable number.

21661652 is a deficient number, since it is larger than the sum of its proper divisors (16637728).

21661652 is a wasteful number, since it uses less digits than its factorization.

21661652 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 55930 (or 55928 counting only the distinct ones).

The product of its digits is 4320, while the sum is 29.

The square root of 21661652 is about 4654.2079884767. The cubic root of 21661652 is about 278.7600442800.

The spelling of 21661652 in words is "twenty-one million, six hundred sixty-one thousand, six hundred fifty-two".