2157189797 has 4 divisors (see below), whose sum is σ = 2465359776. Its totient is φ = 1849019820.

The previous prime is 2157189781. The next prime is 2157189809. The reversal of 2157189797 is 7979817512.

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.

It is a cyclic number.

It is not a de Polignac number, because 2157189797 - 2⁴ = 2157189781 is a prime.

It is a super-3 number, since 3×2157189797³ (a number of 29 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2157189767) 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, 154084979 + ... + 154084992.

It is an arithmetic number, because the mean of its divisors is an integer number (616339944).

Almost surely, 2^2157189797 is an apocalyptic number.

It is an amenable number.

2157189797 is a deficient number, since it is larger than the sum of its proper divisors (308169979).

2157189797 is an equidigital number, since it uses as much as digits as its factorization.

2157189797 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 308169978.

The product of its digits is 2222640, while the sum is 56.

The square root of 2157189797 is about 46445.5573440561. The cubic root of 2157189797 is about 1292.0999782451.

The spelling of 2157189797 in words is "two billion, one hundred fifty-seven million, one hundred eighty-nine thousand, seven hundred ninety-seven".