20781696 has 128 divisors (see below), whose sum is σ = 62375040. Its totient is φ = 6082560.

The previous prime is 20781689. The next prime is 20781697. The reversal of 20781696 is 69618702.

It is a tau number, because it is divible by the number of its divisors (128).

It is a Harshad number since it is a multiple of its sum of digits (39).

It is not an unprimeable number, because it can be changed into a prime (20781697) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 114726 + ... + 114906.

It is an arithmetic number, because the mean of its divisors is an integer number (487305).

Almost surely, 2^20781696 is an apocalyptic number.

20781696 is a gapful number since it is divisible by the number (26) 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 20781696, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31187520).

20781696 is an abundant number, since it is smaller than the sum of its proper divisors (41593344).

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

20781696 is a wasteful number, since it uses less digits than its factorization.

20781696 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 234 (or 222 counting only the distinct ones).

The product of its (nonzero) digits is 36288, while the sum is 39.

The square root of 20781696 is about 4558.6945499781. The cubic root of 20781696 is about 274.9330790330.

The spelling of 20781696 in words is "twenty million, seven hundred eighty-one thousand, six hundred ninety-six".