21642516 has 54 divisors (see below), whose sum is σ = 63644490. Its totient is φ = 6183072.

The previous prime is 21642503. The next prime is 21642527. The reversal of 21642516 is 61524612.

21642516 is a `hidden beast` number, since 2 + 1 + 642 + 5 + 16 = 666.

It can be written as a sum of positive squares in only one way, i.e., 21344400 + 298116 = 4620^2 + 546^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21642516.

It is a congruent number.

It is an unprimeable number.

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 17 ways as a sum of consecutive naturals, for example, 4371 + ... + 7898.

Almost surely, 2^21642516 is an apocalyptic number.

It is an amenable number.

21642516 is an abundant number, since it is smaller than the sum of its proper divisors (42001974).

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

21642516 is a wasteful number, since it uses less digits than its factorization.

21642516 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12293 (or 12281 counting only the distinct ones).

The product of its digits is 2880, while the sum is 27.

The square root of 21642516 is about 4652.1517602073. The cubic root of 21642516 is about 278.6779341409.

The spelling of 21642516 in words is "twenty-one million, six hundred forty-two thousand, five hundred sixteen".