20655690 has 64 divisors (see below), whose sum is σ = 55147392. Its totient is φ = 4908800.

The previous prime is 20655689. The next prime is 20655707. The reversal of 20655690 is 9655602.

It is a super-2 number, since 2×20655690² = 853315058752200, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 16900 + ... + 18080.

It is an arithmetic number, because the mean of its divisors is an integer number (861678).

Almost surely, 2^20655690 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20655690, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27573696).

20655690 is an abundant number, since it is smaller than the sum of its proper divisors (34491702).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20655690 is a wasteful number, since it uses less digits than its factorization.

20655690 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1255.

The product of its (nonzero) digits is 16200, while the sum is 33.

The square root of 20655690 is about 4544.8531329406. The cubic root of 20655690 is about 274.3762834123.

The spelling of 20655690 in words is "twenty million, six hundred fifty-five thousand, six hundred ninety".