7870921 has 4 divisors (see below), whose sum is σ = 8285200. Its totient is φ = 7456644.

The previous prime is 7870909. The next prime is 7870937. The reversal of 7870921 is 1290787.

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 an emirpimes, since its reverse is a distinct semiprime: 1290787 = 149 ⋅8663.

It is a cyclic number.

It is not a de Polignac number, because 7870921 - 2⁹ = 7870409 is a prime.

It is an alternating number because its digits alternate between odd and even.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (7870321) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 207111 + ... + 207148.

It is an arithmetic number, because the mean of its divisors is an integer number (2071300).

Almost surely, 2^7870921 is an apocalyptic number.

It is an amenable number.

7870921 is a deficient number, since it is larger than the sum of its proper divisors (414279).

7870921 is a wasteful number, since it uses less digits than its factorization.

7870921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 414278.

The product of its (nonzero) digits is 7056, while the sum is 34.

The square root of 7870921 is about 2805.5161735410. The cubic root of 7870921 is about 198.9185040404.

The spelling of 7870921 in words is "seven million, eight hundred seventy thousand, nine hundred twenty-one".