20780664 has 96 divisors (see below), whose sum is σ = 57911760. Its totient is φ = 6190080.

The previous prime is 20780659. The next prime is 20780689. The reversal of 20780664 is 46608702.

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

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 392062 + ... + 392114.

Almost surely, 2^20780664 is an apocalyptic number.

20780664 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 20780664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28955880).

20780664 is an abundant number, since it is smaller than the sum of its proper divisors (37131096).

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

20780664 is a wasteful number, since it uses less digits than its factorization.

20780664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 141 (or 106 counting only the distinct ones).

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

The square root of 20780664 is about 4558.5813582736. The cubic root of 20780664 is about 274.9285279826.

The spelling of 20780664 in words is "twenty million, seven hundred eighty thousand, six hundred sixty-four".