20729970 has 72 divisors (see below), whose sum is σ = 57326724. Its totient is φ = 5196288.

The previous prime is 20729939. The next prime is 20729981. The reversal of 20729970 is 7992702.

It can be written as a sum of positive squares in 6 ways, for example, as 14722569 + 6007401 = 3837^2 + 2451^2 .

It is a Curzon 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 35 ways as a sum of consecutive naturals, for example, 25612 + ... + 26408.

Almost surely, 2^20729970 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20729970, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28663362).

20729970 is an abundant number, since it is smaller than the sum of its proper divisors (36596754).

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

20729970 is a wasteful number, since it uses less digits than its factorization.

20729970 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 844 (or 824 counting only the distinct ones).

The product of its (nonzero) digits is 15876, while the sum is 36.

The square root of 20729970 is about 4553.0176806158. The cubic root of 20729970 is about 274.7047851261.

The spelling of 20729970 in words is "twenty million, seven hundred twenty-nine thousand, nine hundred seventy".