20931456 has 128 divisors (see below), whose sum is σ = 68544000. Its totient is φ = 5511168.

The previous prime is 20931451. The next prime is 20931457. The reversal of 20931456 is 65413902.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20931451) 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, 34645 + ... + 35243.

It is an arithmetic number, because the mean of its divisors is an integer number (535500).

Almost surely, 2^20931456 is an apocalyptic number.

20931456 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 20931456, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34272000).

20931456 is an abundant number, since it is smaller than the sum of its proper divisors (47612544).

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

20931456 is a wasteful number, since it uses less digits than its factorization.

20931456 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 636 (or 624 counting only the distinct ones).

The product of its (nonzero) digits is 6480, while the sum is 30.

The square root of 20931456 is about 4575.0908187707. The cubic root of 20931456 is about 275.5919195082.

The spelling of 20931456 in words is "twenty million, nine hundred thirty-one thousand, four hundred fifty-six".