20406388 has 24 divisors (see below), whose sum is σ = 36934632. Its totient is φ = 9857664.

The previous prime is 20406383. The next prime is 20406403. The reversal of 20406388 is 88360402.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 11573604 + 8832784 = 3402^2 + 2972^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20406383) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 25206 + ... + 26002.

It is an arithmetic number, because the mean of its divisors is an integer number (1538943).

Almost surely, 2^20406388 is an apocalyptic number.

It is an amenable number.

20406388 is a deficient number, since it is larger than the sum of its proper divisors (16528244).

20406388 is a wasteful number, since it uses less digits than its factorization.

20406388 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1011 (or 1009 counting only the distinct ones).

The product of its (nonzero) digits is 9216, while the sum is 31.

The square root of 20406388 is about 4517.3430243894. The cubic root of 20406388 is about 273.2679591159.

The spelling of 20406388 in words is "twenty million, four hundred six thousand, three hundred eighty-eight".