21051400 has 48 divisors (see below), whose sum is σ = 49706640. Its totient is φ = 8289600.

The previous prime is 21051397. The next prime is 21051403. The reversal of 21051400 is 415012.

It is an interprime number because it is at equal distance from previous prime (21051397) and next prime (21051403).

It is a super-2 number, since 2×21051400² = 886322883920000, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21051403) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 12615 + ... + 14185.

It is an arithmetic number, because the mean of its divisors is an integer number (1035555).

Almost surely, 2^21051400 is an apocalyptic number.

21051400 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 21051400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24853320).

21051400 is an abundant number, since it is smaller than the sum of its proper divisors (28655240).

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

21051400 is a wasteful number, since it uses less digits than its factorization.

21051400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1654 (or 1645 counting only the distinct ones).

The product of its (nonzero) digits is 40, while the sum is 13.

The square root of 21051400 is about 4588.1804672441. The cubic root of 21051400 is about 276.1173274188.

Adding to 21051400 its reverse (415012), we get a palindrome (21466412).

The spelling of 21051400 in words is "twenty-one million, fifty-one thousand, four hundred".