20669391 has 8 divisors (see below), whose sum is σ = 30621360. Its totient is φ = 13779576.

The previous prime is 20669381. The next prime is 20669393. The reversal of 20669391 is 19396602.

20669391 is a `hidden beast` number, since 206 + 69 + 391 = 666.

It is not a de Polignac number, because 20669391 - 2¹⁰ = 20668367 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20669393) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 382740 + ... + 382793.

It is an arithmetic number, because the mean of its divisors is an integer number (3827670).

Almost surely, 2^20669391 is an apocalyptic number.

20669391 is a deficient number, since it is larger than the sum of its proper divisors (9951969).

20669391 is an equidigital number, since it uses as much as digits as its factorization.

20669391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 765542 (or 765536 counting only the distinct ones).

The product of its (nonzero) digits is 17496, while the sum is 36.

The square root of 20669391 is about 4546.3601925056. The cubic root of 20669391 is about 274.4369349583.

The spelling of 20669391 in words is "twenty million, six hundred sixty-nine thousand, three hundred ninety-one".