21008178101 has 8 divisors (see below), whose sum is σ = 21119473080. Its totient is φ = 20897053632.

The previous prime is 21008178041. The next prime is 21008178133. The reversal of 21008178101 is 10187180012.

It can be written as a sum of positive squares in 4 ways, for example, as 17689266001 + 3318912100 = 133001^2 + 57610^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 21008178101 - 2¹⁴ = 21008161717 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21008178151) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 208331 + ... + 292263.

It is an arithmetic number, because the mean of its divisors is an integer number (2639934135).

Almost surely, 2^21008178101 is an apocalyptic number.

It is an amenable number.

21008178101 is a deficient number, since it is larger than the sum of its proper divisors (111294979).

21008178101 is a wasteful number, since it uses less digits than its factorization.

21008178101 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 85255.

The product of its (nonzero) digits is 896, while the sum is 29.

The spelling of 21008178101 in words is "twenty-one billion, eight million, one hundred seventy-eight thousand, one hundred one".