21005313634 has 8 divisors (see below), whose sum is σ = 31906805760. Its totient is φ = 10369711716.

The previous prime is 21005313631. The next prime is 21005313647. The reversal of 21005313634 is 43631350012.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not an unprimeable number, because it can be changed into a prime (21005313631) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 66472354 + ... + 66472669.

It is an arithmetic number, because the mean of its divisors is an integer number (3988350720).

Almost surely, 2^21005313634 is an apocalyptic number.

21005313634 is a deficient number, since it is larger than the sum of its proper divisors (10901492126).

21005313634 is a wasteful number, since it uses less digits than its factorization.

21005313634 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 132945104.

The product of its (nonzero) digits is 6480, while the sum is 28.

Adding to 21005313634 its reverse (43631350012), we get a palindrome (64636663646).

The spelling of 21005313634 in words is "twenty-one billion, five million, three hundred thirteen thousand, six hundred thirty-four".