20400231 has 4 divisors (see below), whose sum is σ = 27200312. Its totient is φ = 13600152.

The previous prime is 20400197. The next prime is 20400239. The reversal of 20400231 is 13200402.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 20400231 - 2¹⁷ = 20269159 is a prime.

It is a super-2 number, since 2×20400231² = 832338849706722, 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 (20400239) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 3400036 + ... + 3400041.

It is an arithmetic number, because the mean of its divisors is an integer number (6800078).

Almost surely, 2^20400231 is an apocalyptic number.

20400231 is a deficient number, since it is larger than the sum of its proper divisors (6800081).

20400231 is an equidigital number, since it uses as much as digits as its factorization.

20400231 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6800080.

The product of its (nonzero) digits is 48, while the sum is 12.

The square root of 20400231 is about 4516.6614883119. The cubic root of 20400231 is about 273.2404729505.

Adding to 20400231 its reverse (13200402), we get a palindrome (33600633).

The spelling of 20400231 in words is "twenty million, four hundred thousand, two hundred thirty-one".