21948538 has 4 divisors (see below), whose sum is σ = 32922810. Its totient is φ = 10974268.

The previous prime is 21948529. The next prime is 21948551. The reversal of 21948538 is 83584912.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 16345849 + 5602689 = 4043^2 + 2367^2 .

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a self number, because there is not a number n which added to its sum of digits gives 21948538.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5487133 + ... + 5487136.

Almost surely, 2^21948538 is an apocalyptic number.

21948538 is a deficient number, since it is larger than the sum of its proper divisors (10974272).

21948538 is a wasteful number, since it uses less digits than its factorization.

21948538 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10974271.

The product of its digits is 69120, while the sum is 40.

The square root of 21948538 is about 4684.9266803228. The cubic root of 21948538 is about 279.9852798384.

The spelling of 21948538 in words is "twenty-one million, nine hundred forty-eight thousand, five hundred thirty-eight".