7891621 has 4 divisors (see below), whose sum is σ = 8355852. Its totient is φ = 7427392.

The previous prime is 7891613. The next prime is 7891649. The reversal of 7891621 is 1261987.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1261987 = 23 ⋅54869.

It can be written as a sum of positive squares in 2 ways, for example, as 3290596 + 4601025 = 1814^2 + 2145^2 .

It is a cyclic number.

It is not a de Polignac number, because 7891621 - 2³ = 7891613 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (7891651) 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, 232090 + ... + 232123.

It is an arithmetic number, because the mean of its divisors is an integer number (2088963).

Almost surely, 2^7891621 is an apocalyptic number.

It is an amenable number.

7891621 is a deficient number, since it is larger than the sum of its proper divisors (464231).

7891621 is a wasteful number, since it uses less digits than its factorization.

7891621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 464230.

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

The square root of 7891621 is about 2809.2029118595. The cubic root of 7891621 is about 199.0927322159.

The spelling of 7891621 in words is "seven million, eight hundred ninety-one thousand, six hundred twenty-one".