100821409 has 8 divisors (see below), whose sum is σ = 108861480. Its totient is φ = 92822016.

The previous prime is 100821377. The next prime is 100821421. The reversal of 100821409 is 904128001.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 1380625 + 99440784 = 1175^2 + 9972^2 .

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 100821409 - 2⁵ = 100821377 is a prime.

It is not an unprimeable number, because it can be changed into a prime (100821209) 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, 4912 + ... + 15025.

It is an arithmetic number, because the mean of its divisors is an integer number (13607685).

Almost surely, 2^100821409 is an apocalyptic number.

It is an amenable number.

100821409 is a deficient number, since it is larger than the sum of its proper divisors (8040071).

100821409 is a wasteful number, since it uses less digits than its factorization.

100821409 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20339.

The product of its (nonzero) digits is 576, while the sum is 25.

The square root of 100821409 is about 10040.9864555232. The cubic root of 100821409 is about 465.4263003913.

The spelling of 100821409 in words is "one hundred million, eight hundred twenty-one thousand, four hundred nine".