999976421 has 4 divisors (see below), whose sum is σ = 1000040832. Its totient is φ = 999912012.

The previous prime is 999976381. The next prime is 999976423. The reversal of 999976421 is 124679999.

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, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 124679999 = 5821 ⋅21419.

It is a cyclic number.

It is not a de Polignac number, because 999976421 - 2¹⁴ = 999960037 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 10.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (999976423) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6956 + ... + 45258.

It is an arithmetic number, because the mean of its divisors is an integer number (250010208).

Almost surely, 2^999976421 is an apocalyptic number.

It is an amenable number.

999976421 is a deficient number, since it is larger than the sum of its proper divisors (64411).

999976421 is a wasteful number, since it uses less digits than its factorization.

999976421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 64410.

The product of its digits is 2204496, while the sum is 56.

The square root of 999976421 is about 31622.4037827614. The cubic root of 999976421 is about 999.9921402716.

It can be divided in two parts, 999 and 976421, that multiplied together give a palindrome (975444579).

The spelling of 999976421 in words is "nine hundred ninety-nine million, nine hundred seventy-six thousand, four hundred twenty-one".