20647680 has 144 divisors (see below), whose sum is σ = 69659520. Its totient is φ = 5197824.

The previous prime is 20647663. The next prime is 20647703. The reversal of 20647680 is 8674602.

It is a hoax number, since the sum of its digits (33) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 72819 + ... + 73101.

Almost surely, 2^20647680 is an apocalyptic number.

20647680 is a gapful number since it is divisible by the number (20) 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 20647680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34829760).

20647680 is an abundant number, since it is smaller than the sum of its proper divisors (49011840).

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

20647680 is a wasteful number, since it uses less digits than its factorization.

20647680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 326 (or 312 counting only the distinct ones).

The product of its (nonzero) digits is 16128, while the sum is 33.

The square root of 20647680 is about 4543.9718308986. The cubic root of 20647680 is about 274.3408123440.

The spelling of 20647680 in words is "twenty million, six hundred forty-seven thousand, six hundred eighty".