20690381 has 4 divisors (see below), whose sum is σ = 20701212. Its totient is φ = 20679552.

The previous prime is 20690357. The next prime is 20690393. The reversal of 20690381 is 18309602.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 12040900 + 8649481 = 3470^2 + 2941^2 .

It is a cyclic number.

It is not a de Polignac number, because 20690381 - 2¹⁴ = 20673997 is a prime.

It is a super-2 number, since 2×20690381² = 856183731850322, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20693381) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1700 + ... + 6653.

It is an arithmetic number, because the mean of its divisors is an integer number (5175303).

Almost surely, 2^20690381 is an apocalyptic number.

It is an amenable number.

20690381 is a deficient number, since it is larger than the sum of its proper divisors (10831).

20690381 is an equidigital number, since it uses as much as digits as its factorization.

20690381 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10830.

The product of its (nonzero) digits is 2592, while the sum is 29.

The square root of 20690381 is about 4548.6680468023. The cubic root of 20690381 is about 274.5298014654.

Adding to 20690381 its reverse (18309602), we get a palindrome (38999983).

The spelling of 20690381 in words is "twenty million, six hundred ninety thousand, three hundred eighty-one".