21000460 has 72 divisors (see below), whose sum is σ = 49638960. Its totient is φ = 7416576.

The previous prime is 21000433. The next prime is 21000461. The reversal of 21000460 is 6400012.

It is a Harshad number since it is a multiple of its sum of digits (13).

It is a self number, because there is not a number n which added to its sum of digits gives 21000460.

It is not an unprimeable number, because it can be changed into a prime (21000461) 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, 355911 + ... + 355969.

It is an arithmetic number, because the mean of its divisors is an integer number (689430).

Almost surely, 2^21000460 is an apocalyptic number.

21000460 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 21000460, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24819480).

21000460 is an abundant number, since it is smaller than the sum of its proper divisors (28638500).

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

21000460 is a wasteful number, since it uses less digits than its factorization.

21000460 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 155 (or 116 counting only the distinct ones).

The product of its (nonzero) digits is 48, while the sum is 13.

The square root of 21000460 is about 4582.6258847957. The cubic root of 21000460 is about 275.8944320760.

Adding to 21000460 its reverse (6400012), we get a palindrome (27400472).

The spelling of 21000460 in words is "twenty-one million, four hundred sixty", and thus it is an aban number.