21507700 has 18 divisors (see below), whose sum is σ = 46671926. Its totient is φ = 8603040.

The previous prime is 21507667. The next prime is 21507701. The reversal of 21507700 is 770512.

It can be written as a sum of positive squares in 3 ways, for example, as 659344 + 20848356 = 812^2 + 4566^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21507701) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 107439 + ... + 107638.

Almost surely, 2^21507700 is an apocalyptic number.

21507700 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21507700 is an abundant number, since it is smaller than the sum of its proper divisors (25164226).

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

21507700 is a wasteful number, since it uses less digits than its factorization.

21507700 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 215091 (or 215084 counting only the distinct ones).

The product of its (nonzero) digits is 490, while the sum is 22.

The square root of 21507700 is about 4637.6394857729. The cubic root of 21507700 is about 278.0980797073.

The spelling of 21507700 in words is "twenty-one million, five hundred seven thousand, seven hundred".