21542782 has 4 divisors (see below), whose sum is σ = 32314176. Its totient is φ = 10771390.

The previous prime is 21542777. The next prime is 21542783. The reversal of 21542782 is 28724512.

It is a happy number.

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

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21542783) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5385694 + ... + 5385697.

It is an arithmetic number, because the mean of its divisors is an integer number (8078544).

Almost surely, 2^21542782 is an apocalyptic number.

21542782 is a deficient number, since it is larger than the sum of its proper divisors (10771394).

21542782 is a wasteful number, since it uses less digits than its factorization.

21542782 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10771393.

The product of its digits is 8960, while the sum is 31.

The square root of 21542782 is about 4641.4202567749. The cubic root of 21542782 is about 278.2492029026.

The spelling of 21542782 in words is "twenty-one million, five hundred forty-two thousand, seven hundred eighty-two".