100781021 has 12 divisors (see below), whose sum is σ = 112345632. Its totient is φ = 90321000.

The previous prime is 100780973. The next prime is 100781033. The reversal of 100781021 is 120187001.

It is not a de Polignac number, because 100781021 - 2¹⁸ = 100518877 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 100780984 and 100781002.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (100781041) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2726 + ... + 14456.

It is an arithmetic number, because the mean of its divisors is an integer number (9362136).

Almost surely, 2^100781021 is an apocalyptic number.

100781021 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

100781021 is a deficient number, since it is larger than the sum of its proper divisors (11564611).

100781021 is a wasteful number, since it uses less digits than its factorization.

100781021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11824 (or 11813 counting only the distinct ones).

The product of its (nonzero) digits is 112, while the sum is 20.

The square root of 100781021 is about 10038.9750970903. The cubic root of 100781021 is about 465.3641437912.

It can be divided in two parts, 1007 and 81021, that added together give a palindrome (82028).

The spelling of 100781021 in words is "one hundred million, seven hundred eighty-one thousand, twenty-one".