101819821821 has 4 divisors (see below), whose sum is σ = 135759762432. Its totient is φ = 67879881212.

The previous prime is 101819821813. The next prime is 101819821837. The reversal of 101819821821 is 128128918101.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 128128918101 = 3 ⋅42709639367.

It is a cyclic number.

It is not a de Polignac number, because 101819821821 - 2³ = 101819821813 is a prime.

It is a super-2 number, since 2×101819821821² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (101819821861) 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, 16969970301 + ... + 16969970306.

It is an arithmetic number, because the mean of its divisors is an integer number (33939940608).

Almost surely, 2^101819821821 is an apocalyptic number.

It is an amenable number.

101819821821 is a deficient number, since it is larger than the sum of its proper divisors (33939940611).

101819821821 is an equidigital number, since it uses as much as digits as its factorization.

101819821821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33939940610.

The product of its (nonzero) digits is 18432, while the sum is 42.

The spelling of 101819821821 in words is "one hundred one billion, eight hundred nineteen million, eight hundred twenty-one thousand, eight hundred twenty-one".