21995984 has 10 divisors (see below), whose sum is σ = 42617250. Its totient is φ = 10997984.

The previous prime is 21995951. The next prime is 21995993. The reversal of 21995984 is 48959912.

It can be written as a sum of positive squares in only one way, i.e., 21418384 + 577600 = 4628^2 + 760^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 687359 + ... + 687390.

It is an arithmetic number, because the mean of its divisors is an integer number (4261725).

Almost surely, 2^21995984 is an apocalyptic number.

It is an amenable number.

21995984 is a deficient number, since it is larger than the sum of its proper divisors (20621266).

21995984 is a wasteful number, since it uses less digits than its factorization.

21995984 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1374757 (or 1374751 counting only the distinct ones).

The product of its digits is 233280, while the sum is 47.

The square root of 21995984 is about 4689.9876332460. The cubic root of 21995984 is about 280.1868820432.

The spelling of 21995984 in words is "twenty-one million, nine hundred ninety-five thousand, nine hundred eighty-four".