20664451 has 4 divisors (see below), whose sum is σ = 21168504. Its totient is φ = 20160400.

The previous prime is 20664437. The next prime is 20664461. The reversal of 20664451 is 15446602.

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

It is a cyclic number.

It is not a de Polignac number, because 20664451 - 2¹⁷ = 20533379 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20664431) 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, 251965 + ... + 252046.

It is an arithmetic number, because the mean of its divisors is an integer number (5292126).

Almost surely, 2^20664451 is an apocalyptic number.

20664451 is a deficient number, since it is larger than the sum of its proper divisors (504053).

20664451 is an equidigital number, since it uses as much as digits as its factorization.

20664451 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 504052.

The product of its (nonzero) digits is 5760, while the sum is 28.

The square root of 20664451 is about 4545.8168682867. The cubic root of 20664451 is about 274.4150696716.

It can be divided in two parts, 20664 and 451, that added together give a triangular number (21115 = T₂₀₅).

The spelling of 20664451 in words is "twenty million, six hundred sixty-four thousand, four hundred fifty-one".