20521642 has 4 divisors (see below), whose sum is σ = 30782466. Its totient is φ = 10260820.

The previous prime is 20521639. The next prime is 20521651. The reversal of 20521642 is 24612502.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 20511841 + 9801 = 4529^2 + 99^2 .

It is a super-2 number, since 2×20521642² = 842275580752328, which contains 22 as substring.

It is a Smith number, since the sum of its digits (22) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax 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, 5130409 + ... + 5130412.

Almost surely, 2^20521642 is an apocalyptic number.

20521642 is a deficient number, since it is larger than the sum of its proper divisors (10260824).

20521642 is a wasteful number, since it uses less digits than its factorization.

20521642 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10260823.

The product of its (nonzero) digits is 960, while the sum is 22.

The square root of 20521642 is about 4530.0818977144. The cubic root of 20521642 is about 273.7814603516.

The spelling of 20521642 in words is "twenty million, five hundred twenty-one thousand, six hundred forty-two".