21730536 has 24 divisors (see below), whose sum is σ = 58853730. Its totient is φ = 7243488.

The previous prime is 21730531. The next prime is 21730537. The reversal of 21730536 is 63503712.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 17690436 + 4040100 = 4206^2 + 2010^2 .

It is a tau number, because it is divible by the number of its divisors (24).

It is not an unprimeable number, because it can be changed into a prime (21730531) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 150835 + ... + 150978.

Almost surely, 2^21730536 is an apocalyptic number.

It is an amenable number.

21730536 is an abundant number, since it is smaller than the sum of its proper divisors (37123194).

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

21730536 is a wasteful number, since it uses less digits than its factorization.

21730536 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 301825 (or 301818 counting only the distinct ones).

The product of its (nonzero) digits is 3780, while the sum is 27.

The square root of 21730536 is about 4661.6022996390. The cubic root of 21730536 is about 279.0552170359.

The spelling of 21730536 in words is "twenty-one million, seven hundred thirty thousand, five hundred thirty-six".