21005100642 has 8 divisors (see below), whose sum is σ = 42010201296. Its totient is φ = 7001700212.

The previous prime is 21005100581. The next prime is 21005100643. The reversal of 21005100642 is 24600150012.

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

21005100642 is an admirable number.

It is not an unprimeable number, because it can be changed into a prime (21005100643) 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, 1750425048 + ... + 1750425059.

It is an arithmetic number, because the mean of its divisors is an integer number (5251275162).

Almost surely, 2^21005100642 is an apocalyptic number.

21005100642 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

21005100642 is a wasteful number, since it uses less digits than its factorization.

21005100642 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3500850112.

The product of its (nonzero) digits is 480, while the sum is 21.

Adding to 21005100642 its reverse (24600150012), we get a palindrome (45605250654).

The spelling of 21005100642 in words is "twenty-one billion, five million, one hundred thousand, six hundred forty-two".