21000700 has 72 divisors (see below), whose sum is σ = 54857600. Its totient is φ = 6816960.

The previous prime is 21000689. The next prime is 21000709. The reversal of 21000700 is 700012.

It is a Harshad number since it is a multiple of its sum of digits (10).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21000709) 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, 12511 + ... + 14089.

Almost surely, 2^21000700 is an apocalyptic number.

21000700 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 21000700, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27428800).

21000700 is an abundant number, since it is smaller than the sum of its proper divisors (33856900).

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

21000700 is a wasteful number, since it uses less digits than its factorization.

21000700 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1619 (or 1612 counting only the distinct ones).

The product of its (nonzero) digits is 14, while the sum is 10.

The square root of 21000700 is about 4582.6520705810. The cubic root of 21000700 is about 275.8954830754.

Adding to 21000700 its reverse (700012), we get a palindrome (21700712).

The spelling of 21000700 in words is "twenty-one million, seven hundred", and thus it is an aban number.