20521667 has 4 divisors (see below), whose sum is σ = 20769000. Its totient is φ = 20274336.

The previous prime is 20521663. The next prime is 20521673. The reversal of 20521667 is 76612502.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 76612502 = 2 ⋅38306251.

It is a cyclic number.

It is not a de Polignac number, because 20521667 - 2² = 20521663 is a prime.

It is a super-2 number, since 2×20521667² = 842277632917778, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20521661) by changing a digit.

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, 123542 + ... + 123707.

It is an arithmetic number, because the mean of its divisors is an integer number (5192250).

Almost surely, 2^20521667 is an apocalyptic number.

20521667 is a deficient number, since it is larger than the sum of its proper divisors (247333).

20521667 is an equidigital number, since it uses as much as digits as its factorization.

20521667 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 247332.

The product of its (nonzero) digits is 5040, while the sum is 29.

The square root of 20521667 is about 4530.0846570456. The cubic root of 20521667 is about 273.7815715274.

The spelling of 20521667 in words is "twenty million, five hundred twenty-one thousand, six hundred sixty-seven".