20661655 has 32 divisors (see below), whose sum is σ = 29675520. Its totient is φ = 13512960.

The previous prime is 20661643. The next prime is 20661689. The reversal of 20661655 is 55616602.

It is not a de Polignac number, because 20661655 - 2⁹ = 20661143 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (31).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 148576 + ... + 148714.

It is an arithmetic number, because the mean of its divisors is an integer number (927360).

Almost surely, 2^20661655 is an apocalyptic number.

20661655 is a deficient number, since it is larger than the sum of its proper divisors (9013865).

20661655 is a wasteful number, since it uses less digits than its factorization.

20661655 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 319.

The product of its (nonzero) digits is 10800, while the sum is 31.

The square root of 20661655 is about 4545.5093223972. The cubic root of 20661655 is about 274.4026925521.

It can be divided in two parts, 20661 and 655, that added together give a square (21316 = 146²).

The spelling of 20661655 in words is "twenty million, six hundred sixty-one thousand, six hundred fifty-five".