20155217 has 4 divisors (see below), whose sum is σ = 21340836. Its totient is φ = 18969600.

The previous prime is 20155169. The next prime is 20155249. The reversal of 20155217 is 71255102.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 15928081 + 4227136 = 3991^2 + 2056^2 .

It is a cyclic number.

It is not a de Polignac number, because 20155217 - 2⁸ = 20154961 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20155192 and 20155201.

It is not an unprimeable number, because it can be changed into a prime (20155277) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 592784 + ... + 592817.

It is an arithmetic number, because the mean of its divisors is an integer number (5335209).

Almost surely, 2^20155217 is an apocalyptic number.

It is an amenable number.

20155217 is a deficient number, since it is larger than the sum of its proper divisors (1185619).

20155217 is a wasteful number, since it uses less digits than its factorization.

20155217 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1185618.

The product of its (nonzero) digits is 700, while the sum is 23.

The square root of 20155217 is about 4489.4562031498. The cubic root of 20155217 is about 272.1421591443.

The spelling of 20155217 in words is "twenty million, one hundred fifty-five thousand, two hundred seventeen".