20709645 has 32 divisors (see below), whose sum is σ = 36353664. Its totient is φ = 9984000.

The previous prime is 20709641. The next prime is 20709653. The reversal of 20709645 is 54690702.

It is not a de Polignac number, because 20709645 - 2² = 20709641 is a prime.

It is a super-3 number, since 3×20709645³ (a number of 23 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20709641) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 51445 + ... + 51845.

It is an arithmetic number, because the mean of its divisors is an integer number (1136052).

Almost surely, 2^20709645 is an apocalyptic number.

It is an amenable number.

20709645 is a deficient number, since it is larger than the sum of its proper divisors (15644019).

20709645 is a wasteful number, since it uses less digits than its factorization.

20709645 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 733.

The product of its (nonzero) digits is 15120, while the sum is 33.

The square root of 20709645 is about 4550.7850971014. The cubic root of 20709645 is about 274.6149763368.

The spelling of 20709645 in words is "twenty million, seven hundred nine thousand, six hundred forty-five".