21051700 has 36 divisors (see below), whose sum is σ = 46059552. Its totient is φ = 8351200.

The previous prime is 21051691. The next prime is 21051703. The reversal of 21051700 is 715012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21051703) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 12297 + ... + 13903.

It is an arithmetic number, because the mean of its divisors is an integer number (1279432).

Almost surely, 2^21051700 is an apocalyptic number.

21051700 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 21051700, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23029776).

21051700 is an abundant number, since it is smaller than the sum of its proper divisors (25007852).

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

21051700 is a wasteful number, since it uses less digits than its factorization.

21051700 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1752 (or 1745 counting only the distinct ones).

The product of its (nonzero) digits is 70, while the sum is 16.

The square root of 21051700 is about 4588.2131598259. The cubic root of 21051700 is about 276.1186390466.

Adding to 21051700 its reverse (715012), we get a palindrome (21766712).

The spelling of 21051700 in words is "twenty-one million, fifty-one thousand, seven hundred".