21002012138 has 8 divisors (see below), whose sum is σ = 31503972288. Its totient is φ = 10500688044.

The previous prime is 21002012137. The next prime is 21002012147. The reversal of 21002012138 is 83121020012.

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 (21002012137) 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, 65456 + ... + 215147.

It is an arithmetic number, because the mean of its divisors is an integer number (3937996536).

Almost surely, 2^21002012138 is an apocalyptic number.

21002012138 is a deficient number, since it is larger than the sum of its proper divisors (10501960150).

21002012138 is a wasteful number, since it uses less digits than its factorization.

21002012138 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 318028.

The product of its (nonzero) digits is 192, while the sum is 20.

The spelling of 21002012138 in words is "twenty-one billion, two million, twelve thousand, one hundred thirty-eight".