20431290 has 64 divisors (see below), whose sum is σ = 54110592. Its totient is φ = 4896000.

The previous prime is 20431277. The next prime is 20431303. The reversal of 20431290 is 9213402.

It is an interprime number because it is at equal distance from previous prime (20431277) and next prime (20431303).

It is a super-2 number, since 2×20431290² = 834875222128200, which contains 22 as substring.

It is a Curzon 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, 33024 + ... + 33636.

It is an arithmetic number, because the mean of its divisors is an integer number (845478).

Almost surely, 2^20431290 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20431290, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27055296).

20431290 is an abundant number, since it is smaller than the sum of its proper divisors (33679302).

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

20431290 is a wasteful number, since it uses less digits than its factorization.

20431290 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 735.

The product of its (nonzero) digits is 432, while the sum is 21.

The square root of 20431290 is about 4520.0984502553. The cubic root of 20431290 is about 273.3790706066.

Adding to 20431290 its reverse (9213402), we get a palindrome (29644692).

It can be divided in two parts, 204312 and 90, that added together give a palindrome (204402).

The spelling of 20431290 in words is "twenty million, four hundred thirty-one thousand, two hundred ninety".