20729646 has 72 divisors (see below), whose sum is σ = 55041480. Its totient is φ = 5606496.

The previous prime is 20729633. The next prime is 20729699. The reversal of 20729646 is 64692702.

It is a happy number.

20729646 is a `hidden beast` number, since 2 + 0 + 7 + 2 + 9 + 646 = 666.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 20729646.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 16140 + ... + 17376.

It is an arithmetic number, because the mean of its divisors is an integer number (764465).

Almost surely, 2^20729646 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20729646, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27520740).

20729646 is an abundant number, since it is smaller than the sum of its proper divisors (34311834).

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

20729646 is a wasteful number, since it uses less digits than its factorization.

20729646 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1278 (or 1268 counting only the distinct ones).

The product of its (nonzero) digits is 36288, while the sum is 36.

The square root of 20729646 is about 4552.9820996793. The cubic root of 20729646 is about 274.7033539483.

The spelling of 20729646 in words is "twenty million, seven hundred twenty-nine thousand, six hundred forty-six".