20669749 has 4 divisors (see below), whose sum is σ = 20729664. Its totient is φ = 20609836.

The previous prime is 20669729. The next prime is 20669767. The reversal of 20669749 is 94796602.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 20669749 - 2²³ = 12281141 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20669729) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 29437 + ... + 30130.

It is an arithmetic number, because the mean of its divisors is an integer number (5182416).

Almost surely, 2^20669749 is an apocalyptic number.

It is an amenable number.

20669749 is a deficient number, since it is larger than the sum of its proper divisors (59915).

20669749 is an equidigital number, since it uses as much as digits as its factorization.

20669749 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 59914.

The product of its (nonzero) digits is 163296, while the sum is 43.

The square root of 20669749 is about 4546.3995644906. The cubic root of 20669749 is about 274.4385193923.

The spelling of 20669749 in words is "twenty million, six hundred sixty-nine thousand, seven hundred forty-nine".