21649536 has 48 divisors (see below), whose sum is σ = 62302110. Its totient is φ = 7216128.

The previous prime is 21649499. The next prime is 21649541. The reversal of 21649536 is 63594612.

It is a happy number.

21649536 is a `hidden beast` number, since 2 + 1 + 649 + 5 + 3 + 6 = 666.

It can be written as a sum of positive squares in only one way, i.e., 16451136 + 5198400 = 4056^2 + 2280^2 .

It is a tau number, because it is divible by the number of its divisors (48).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a self number, because there is not a number n which added to its sum of digits gives 21649536.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 8245 + ... + 10548.

Almost surely, 2^21649536 is an apocalyptic number.

It is an amenable number.

21649536 is an abundant number, since it is smaller than the sum of its proper divisors (40652574).

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

21649536 is a wasteful number, since it uses less digits than its factorization.

21649536 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18813 (or 18798 counting only the distinct ones).

The product of its digits is 38880, while the sum is 36.

The square root of 21649536 is about 4652.9061886094. The cubic root of 21649536 is about 278.7080616858.

The spelling of 21649536 in words is "twenty-one million, six hundred forty-nine thousand, five hundred thirty-six".