691221121 has 8 divisors (see below), whose sum is σ = 727858080. Its totient is φ = 654609888.

The previous prime is 691221109. The next prime is 691221133. The reversal of 691221121 is 121122196.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (691221109) and next prime (691221133).

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 691221121 - 2¹¹ = 691219073 is a prime.

It is not an unprimeable number, because it can be changed into a prime (691221101) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 75810 + ... + 84436.

It is an arithmetic number, because the mean of its divisors is an integer number (90982260).

Almost surely, 2^691221121 is an apocalyptic number.

It is an amenable number.

691221121 is a deficient number, since it is larger than the sum of its proper divisors (36636959).

691221121 is a wasteful number, since it uses less digits than its factorization.

691221121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12863.

The product of its digits is 432, while the sum is 25.

The square root of 691221121 is about 26291.0844394065. The cubic root of 691221121 is about 884.1765654187.

The spelling of 691221121 in words is "six hundred ninety-one million, two hundred twenty-one thousand, one hundred twenty-one".