409899561521 has 16 divisors (see below), whose sum is σ = 444785780880. Its totient is φ = 376218501120.

The previous prime is 409899561509. The next prime is 409899561569. The reversal of 409899561521 is 125165998904.

It can be written as a sum of positive squares in 8 ways, for example, as 11132571121 + 398766990400 = 105511^2 + 631480^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-409899561521 is a prime.

It is not an unprimeable number, because it can be changed into a prime (409899531521) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1533065 + ... + 1780473.

It is an arithmetic number, because the mean of its divisors is an integer number (27799111305).

Almost surely, 2^409899561521 is an apocalyptic number.

409899561521 is a gapful number since it is divisible by the number (41) formed by its first and last digit.

It is an amenable number.

409899561521 is a deficient number, since it is larger than the sum of its proper divisors (34886219359).

409899561521 is a wasteful number, since it uses less digits than its factorization.

409899561521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 249844.

The product of its (nonzero) digits is 6998400, while the sum is 59.

The spelling of 409899561521 in words is "four hundred nine billion, eight hundred ninety-nine million, five hundred sixty-one thousand, five hundred twenty-one".