7861921 has 4 divisors (see below), whose sum is σ = 7880112. Its totient is φ = 7843732.

The previous prime is 7861907. The next prime is 7861933. The reversal of 7861921 is 1291687.

It is a happy number.

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: 1291687 = 59 ⋅21893.

It is a cyclic number.

It is not a de Polignac number, because 7861921 - 2⁷ = 7861793 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (7861951) 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, 8431 + ... + 9316.

It is an arithmetic number, because the mean of its divisors is an integer number (1970028).

Almost surely, 2^7861921 is an apocalyptic number.

It is an amenable number.

7861921 is a deficient number, since it is larger than the sum of its proper divisors (18191).

7861921 is a wasteful number, since it uses less digits than its factorization.

7861921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18190.

The product of its digits is 6048, while the sum is 34.

The square root of 7861921 is about 2803.9117318489. The cubic root of 7861921 is about 198.8426573752.

The spelling of 7861921 in words is "seven million, eight hundred sixty-one thousand, nine hundred twenty-one".