20903661 has 6 divisors (see below), whose sum is σ = 30194190. Its totient is φ = 13935768.

The previous prime is 20903647. The next prime is 20903681. The reversal of 20903661 is 16630902.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 18404100 + 2499561 = 4290^2 + 1581^2 .

It is not a de Polignac number, because 20903661 - 2²¹ = 18806509 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20903621) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1161306 + ... + 1161323.

It is an arithmetic number, because the mean of its divisors is an integer number (5032365).

Almost surely, 2^20903661 is an apocalyptic number.

It is an amenable number.

20903661 is a deficient number, since it is larger than the sum of its proper divisors (9290529).

20903661 is a wasteful number, since it uses less digits than its factorization.

20903661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2322635 (or 2322632 counting only the distinct ones).

The product of its (nonzero) digits is 1944, while the sum is 27.

The square root of 20903661 is about 4572.0521650567. The cubic root of 20903661 is about 275.4698787780.

The spelling of 20903661 in words is "twenty million, nine hundred three thousand, six hundred sixty-one".