21661522 has 8 divisors (see below), whose sum is σ = 32516172. Its totient is φ = 10822800.

The previous prime is 21661517. The next prime is 21661531. The reversal of 21661522 is 22516612.

It can be written as a sum of positive squares in 2 ways, for example, as 13315201 + 8346321 = 3649^2 + 2889^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

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 in 3 ways as a sum of consecutive naturals, for example, 372 + ... + 6592.

Almost surely, 2^21661522 is an apocalyptic number.

21661522 is a deficient number, since it is larger than the sum of its proper divisors (10854650).

21661522 is a wasteful number, since it uses less digits than its factorization.

21661522 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7964.

The product of its digits is 1440, while the sum is 25.

The square root of 21661522 is about 4654.1940225994. The cubic root of 21661522 is about 278.7594866298.

The spelling of 21661522 in words is "twenty-one million, six hundred sixty-one thousand, five hundred twenty-two".