21180456 has 96 divisors (see below), whose sum is σ = 64022400. Its totient is φ = 6270720.

The previous prime is 21180451. The next prime is 21180463. The reversal of 21180456 is 65408112.

It is a super-2 number, since 2×21180456² = 897223432735872, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21180451) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 36940 + ... + 37508.

It is an arithmetic number, because the mean of its divisors is an integer number (666900).

Almost surely, 2^21180456 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21180456, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32011200).

21180456 is an abundant number, since it is smaller than the sum of its proper divisors (42841944).

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

21180456 is a wasteful number, since it uses less digits than its factorization.

21180456 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 639 (or 632 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 27.

The square root of 21180456 is about 4602.2229411449. Note that the first 3 decimals coincide. The cubic root of 21180456 is about 276.6804257605.

Adding to 21180456 its reverse (65408112), we get a palindrome (86588568).

The spelling of 21180456 in words is "twenty-one million, one hundred eighty thousand, four hundred fifty-six".