20155021 has 2 divisors, whose sum is σ = 20155022. Its totient is φ = 20155020.

The previous prime is 20154961. The next prime is 20155039. The reversal of 20155021 is 12055102.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11088900 + 9066121 = 3330^2 + 3011^2 .

It is a cyclic number.

It is not a de Polignac number, because 20155021 - 2²³ = 11766413 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 20154986 and 20155004.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20155321) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10077510 + 10077511.

It is an arithmetic number, because the mean of its divisors is an integer number (10077511).

Almost surely, 2^20155021 is an apocalyptic number.

It is an amenable number.

20155021 is a deficient number, since it is larger than the sum of its proper divisors (1).

20155021 is an equidigital number, since it uses as much as digits as its factorization.

20155021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 100, while the sum is 16.

The square root of 20155021 is about 4489.4343741723. The cubic root of 20155021 is about 272.1412769900.

The spelling of 20155021 in words is "twenty million, one hundred fifty-five thousand, twenty-one".