21313603506 has 32 divisors (see below), whose sum is σ = 47146938048. Its totient is φ = 6380786880.

The previous prime is 21313603489. The next prime is 21313603513. The reversal of 21313603506 is 60530631312.

It is a happy number.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3689700 + ... + 3695471.

It is an arithmetic number, because the mean of its divisors is an integer number (1473341814).

Almost surely, 2^21313603506 is an apocalyptic number.

21313603506 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

21313603506 is an abundant number, since it is smaller than the sum of its proper divisors (25833334542).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21313603506 is a wasteful number, since it uses less digits than its factorization.

21313603506 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7385226.

The product of its (nonzero) digits is 9720, while the sum is 30.

The spelling of 21313603506 in words is "twenty-one billion, three hundred thirteen million, six hundred three thousand, five hundred six".