21782500906 has 4 divisors (see below), whose sum is σ = 32673751362. Its totient is φ = 10891250452.

The previous prime is 21782500853. The next prime is 21782500913. The reversal of 21782500906 is 60900528712.

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., 17320928881 + 4461572025 = 131609^2 + 66795^2 .

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 an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5445625225 + ... + 5445625228.

Almost surely, 2^21782500906 is an apocalyptic number.

21782500906 is a deficient number, since it is larger than the sum of its proper divisors (10891250456).

21782500906 is a wasteful number, since it uses less digits than its factorization.

21782500906 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10891250455.

The product of its (nonzero) digits is 60480, while the sum is 40.

The spelling of 21782500906 in words is "twenty-one billion, seven hundred eighty-two million, five hundred thousand, nine hundred six".