20156945 has 4 divisors (see below), whose sum is σ = 24188340. Its totient is φ = 16125552.

The previous prime is 20156933. The next prime is 20156959. The reversal of 20156945 is 54965102.

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: 54965102 = 2 ⋅27482551.

It can be written as a sum of positive squares in 2 ways, for example, as 13786369 + 6370576 = 3713^2 + 2524^2 .

It is a cyclic number.

It is not a de Polignac number, because 20156945 - 2²⁴ = 3379729 is a prime.

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, 2015690 + ... + 2015699.

It is an arithmetic number, because the mean of its divisors is an integer number (6047085).

Almost surely, 2^20156945 is an apocalyptic number.

It is an amenable number.

20156945 is a deficient number, since it is larger than the sum of its proper divisors (4031395).

20156945 is an equidigital number, since it uses as much as digits as its factorization.

20156945 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4031394.

The product of its (nonzero) digits is 10800, while the sum is 32.

The square root of 20156945 is about 4489.6486499502. The cubic root of 20156945 is about 272.1499362575.

The spelling of 20156945 in words is "twenty million, one hundred fifty-six thousand, nine hundred forty-five".