100021381 has 4 divisors (see below), whose sum is σ = 100053772. Its totient is φ = 99988992.

The previous prime is 100021379. The next prime is 100021393. The reversal of 100021381 is 183120001.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 20205025 + 79816356 = 4495^2 + 8934^2 .

It is a cyclic number.

It is not a de Polignac number, because 100021381 - 2¹ = 100021379 is a prime.

It is a super-2 number, since 2×100021381² = 20008553314294322, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (100021331) 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, 11010 + ... + 17923.

It is an arithmetic number, because the mean of its divisors is an integer number (25013443).

Almost surely, 2^100021381 is an apocalyptic number.

It is an amenable number.

100021381 is a deficient number, since it is larger than the sum of its proper divisors (32391).

100021381 is an equidigital number, since it uses as much as digits as its factorization.

100021381 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32390.

The product of its (nonzero) digits is 48, while the sum is 16.

The square root of 100021381 is about 10001.0689928627. The cubic root of 100021381 is about 464.1919616075.

Adding to 100021381 its reverse (183120001), we get a palindrome (283141382).

The spelling of 100021381 in words is "one hundred million, twenty-one thousand, three hundred eighty-one".