21661412 has 6 divisors (see below), whose sum is σ = 37907478. Its totient is φ = 10830704.

The previous prime is 21661399. The next prime is 21661421. The reversal of 21661412 is 21416612.

It can be written as a sum of positive squares in only one way, i.e., 10863616 + 10797796 = 3296^2 + 3286^2 .

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, 2707673 + ... + 2707680.

It is an arithmetic number, because the mean of its divisors is an integer number (6317913).

Almost surely, 2^21661412 is an apocalyptic number.

It is an amenable number.

21661412 is a deficient number, since it is larger than the sum of its proper divisors (16246066).

21661412 is a wasteful number, since it uses less digits than its factorization.

21661412 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5415357 (or 5415355 counting only the distinct ones).

The product of its digits is 576, while the sum is 23.

The square root of 21661412 is about 4654.1822052859. The cubic root of 21661412 is about 278.7590147701.

The spelling of 21661412 in words is "twenty-one million, six hundred sixty-one thousand, four hundred twelve".