21530536 has 8 divisors (see below), whose sum is σ = 40369770. Its totient is φ = 10765264.

The previous prime is 21530533. The next prime is 21530539. The reversal of 21530536 is 63503512.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21530533) and next prime (21530539).

It can be written as a sum of positive squares in only one way, i.e., 21436900 + 93636 = 4630^2 + 306^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is a self number, because there is not a number n which added to its sum of digits gives 21530536.

It is not an unprimeable number, because it can be changed into a prime (21530533) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1345651 + ... + 1345666.

Almost surely, 2^21530536 is an apocalyptic number.

It is an amenable number.

21530536 is a deficient number, since it is larger than the sum of its proper divisors (18839234).

21530536 is a wasteful number, since it uses less digits than its factorization.

21530536 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2691323 (or 2691319 counting only the distinct ones).

The product of its (nonzero) digits is 2700, while the sum is 25.

The square root of 21530536 is about 4640.1008609727. The cubic root of 21530536 is about 278.1964692988.

The spelling of 21530536 in words is "twenty-one million, five hundred thirty thousand, five hundred thirty-six".