20729664 has 168 divisors, whose sum is σ = 65973960. Its totient is φ = 6193152.

The previous prime is 20729633. The next prime is 20729699. The reversal of 20729664 is 46692702.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 6350400 + 14379264 = 2520^2 + 3792^2 .

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 283932 + ... + 284004.

Almost surely, 2^20729664 is an apocalyptic number.

20729664 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20729664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32986980).

20729664 is an abundant number, since it is smaller than the sum of its proper divisors (45244296).

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

20729664 is a wasteful number, since it uses less digits than its factorization.

20729664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 137 (or 124 counting only the distinct ones).

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

The square root of 20729664 is about 4552.9840764053. The cubic root of 20729664 is about 274.7034334586.

The spelling of 20729664 in words is "twenty million, seven hundred twenty-nine thousand, six hundred sixty-four".