100821257 has 4 divisors (see below), whose sum is σ = 100841796. Its totient is φ = 100800720.

The previous prime is 100821233. The next prime is 100821289. The reversal of 100821257 is 752128001.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 752128001 = 5683 ⋅132347.

It can be written as a sum of positive squares in 2 ways, for example, as 94848121 + 5973136 = 9739^2 + 2444^2 .

It is a cyclic number.

It is not a de Polignac number, because 100821257 - 2⁸ = 100821001 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (100821557) 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, 1907 + ... + 14327.

It is an arithmetic number, because the mean of its divisors is an integer number (25210449).

Almost surely, 2^100821257 is an apocalyptic number.

It is an amenable number.

100821257 is a deficient number, since it is larger than the sum of its proper divisors (20539).

100821257 is an equidigital number, since it uses as much as digits as its factorization.

100821257 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20538.

The product of its (nonzero) digits is 1120, while the sum is 26.

The square root of 100821257 is about 10040.9788865429. The cubic root of 100821257 is about 465.4260664965.

Adding to 100821257 its reverse (752128001), we get a palindrome (852949258).

The spelling of 100821257 in words is "one hundred million, eight hundred twenty-one thousand, two hundred fifty-seven".