6399408798421 has 4 divisors (see below), whose sum is σ = 6402313661632. Its totient is φ = 6396503935212.

The previous prime is 6399408798383. The next prime is 6399408798451. The reversal of 6399408798421 is 1248978049936.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 6399408798421 - 2⁴¹ = 4200385542869 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6399408798451) 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, 1452428301 + ... + 1452432706.

It is an arithmetic number, because the mean of its divisors is an integer number (1600578415408).

Almost surely, 2^{6399408798421} is an apocalyptic number.

It is an amenable number.

6399408798421 is a deficient number, since it is larger than the sum of its proper divisors (2904863211).

6399408798421 is a wasteful number, since it uses less digits than its factorization.

6399408798421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2904863210.

The product of its (nonzero) digits is 188116992, while the sum is 70.

The spelling of 6399408798421 in words is "six trillion, three hundred ninety-nine billion, four hundred eight million, seven hundred ninety-eight thousand, four hundred twenty-one".