21425633906 has 4 divisors (see below), whose sum is σ = 32138450862. Its totient is φ = 10712816952.

The previous prime is 21425633881. The next prime is 21425633909. The reversal of 21425633906 is 60933652412.

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., 21422713225 + 2920681 = 146365^2 + 1709^2 .

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21425633909) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5356408475 + ... + 5356408478.

Almost surely, 2^21425633906 is an apocalyptic number.

21425633906 is a deficient number, since it is larger than the sum of its proper divisors (10712816956).

21425633906 is a wasteful number, since it uses less digits than its factorization.

21425633906 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10712816955.

The product of its (nonzero) digits is 233280, while the sum is 41.

The spelling of 21425633906 in words is "twenty-one billion, four hundred twenty-five million, six hundred thirty-three thousand, nine hundred six".