20661604 has 12 divisors (see below), whose sum is σ = 36490300. Its totient is φ = 10235808.

The previous prime is 20661587. The next prime is 20661631. The reversal of 20661604 is 40616602.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 5992704 + 14668900 = 2448^2 + 3830^2 .

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, 23259 + ... + 24130.

Almost surely, 2^20661604 is an apocalyptic number.

It is an amenable number.

20661604 is a deficient number, since it is larger than the sum of its proper divisors (15828696).

20661604 is a wasteful number, since it uses less digits than its factorization.

20661604 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 47502 (or 47500 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 25.

The square root of 20661604 is about 4545.5037124614. The cubic root of 20661604 is about 274.4024667788.

The spelling of 20661604 in words is "twenty million, six hundred sixty-one thousand, six hundred four".