21002012136 has 48 divisors (see below), whose sum is σ = 65006229600. Its totient is φ = 6000574752.

The previous prime is 21002012107. The next prime is 21002012137. The reversal of 21002012136 is 63121020012.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is not an unprimeable number, because it can be changed into a prime (21002012137) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 20834826 + ... + 20835833.

It is an arithmetic number, because the mean of its divisors is an integer number (1354296450).

Almost surely, 2^21002012136 is an apocalyptic number.

It is an amenable number.

21002012136 is an abundant number, since it is smaller than the sum of its proper divisors (44004217464).

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

21002012136 is a wasteful number, since it uses less digits than its factorization.

21002012136 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 41670678 (or 41670671 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 18.

Adding to 21002012136 its reverse (63121020012), we get a palindrome (84123032148).

The spelling of 21002012136 in words is "twenty-one billion, two million, twelve thousand, one hundred thirty-six".