20397155 has 4 divisors (see below), whose sum is σ = 24476592. Its totient is φ = 16317720.

The previous prime is 20397137. The next prime is 20397173. The reversal of 20397155 is 55179302.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 55179302 = 2 ⋅27589651.

It is an interprime number because it is at equal distance from previous prime (20397137) and next prime (20397173).

It is not a de Polignac number, because 20397155 - 2²⁰ = 19348579 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2039711 + ... + 2039720.

It is an arithmetic number, because the mean of its divisors is an integer number (6119148).

Almost surely, 2^20397155 is an apocalyptic number.

20397155 is a deficient number, since it is larger than the sum of its proper divisors (4079437).

20397155 is an equidigital number, since it uses as much as digits as its factorization.

20397155 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4079436.

The product of its (nonzero) digits is 9450, while the sum is 32.

The square root of 20397155 is about 4516.3209584794. The cubic root of 20397155 is about 273.2267389566.

The spelling of 20397155 in words is "twenty million, three hundred ninety-seven thousand, one hundred fifty-five".