20813661 has 48 divisors (see below), whose sum is σ = 35380800. Its totient is φ = 11650560.

The previous prime is 20813623. The next prime is 20813669. The reversal of 20813661 is 16631802.

It is not a de Polignac number, because 20813661 - 2¹³ = 20805469 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 (20813669) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 139615 + ... + 139763.

It is an arithmetic number, because the mean of its divisors is an integer number (737100).

Almost surely, 2^20813661 is an apocalyptic number.

It is an amenable number.

20813661 is a deficient number, since it is larger than the sum of its proper divisors (14567139).

20813661 is a wasteful number, since it uses less digits than its factorization.

20813661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 266 (or 263 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 27.

The square root of 20813661 is about 4562.1991407653. The cubic root of 20813661 is about 275.0739679815.

The spelling of 20813661 in words is "twenty million, eight hundred thirteen thousand, six hundred sixty-one".