21987082 has 8 divisors (see below), whose sum is σ = 35517636. Its totient is φ = 10147872.

The previous prime is 21987079. The next prime is 21987083. The reversal of 21987082 is 28078912.

It can be written as a sum of positive squares in 2 ways, for example, as 21986721 + 361 = 4689^2 + 19^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not an unprimeable number, because it can be changed into a prime (21987083) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 422803 + ... + 422854.

Almost surely, 2^21987082 is an apocalyptic number.

21987082 is a deficient number, since it is larger than the sum of its proper divisors (13530554).

21987082 is a wasteful number, since it uses less digits than its factorization.

21987082 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 845672.

The product of its (nonzero) digits is 16128, while the sum is 37.

The square root of 21987082 is about 4689.0384941905. The cubic root of 21987082 is about 280.1490787760.

The spelling of 21987082 in words is "twenty-one million, nine hundred eighty-seven thousand, eighty-two".