20409564 has 24 divisors (see below), whose sum is σ = 54425728. Its totient is φ = 5831280.

The previous prime is 20409547. The next prime is 20409583. The reversal of 20409564 is 46590402.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 121402 + ... + 121569.

Almost surely, 2^20409564 is an apocalyptic number.

It is an amenable number.

20409564 is an abundant number, since it is smaller than the sum of its proper divisors (34016164).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20409564 is a wasteful number, since it uses less digits than its factorization.

20409564 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 242985 (or 242983 counting only the distinct ones).

The product of its (nonzero) digits is 8640, while the sum is 30.

The square root of 20409564 is about 4517.6945447872. The cubic root of 20409564 is about 273.2821352980.

Adding to 20409564 its reverse (46590402), we get a palindrome (66999966).

The spelling of 20409564 in words is "twenty million, four hundred nine thousand, five hundred sixty-four".