20400439 has 2 divisors, whose sum is σ = 20400440. Its totient is φ = 20400438.

The previous prime is 20400437. The next prime is 20400463. The reversal of 20400439 is 93400402.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20400439 - 2¹ = 20400437 is a prime.

It is a super-2 number, since 2×20400439² = 832355822785442, which contains 22 as substring.

Together with 20400437, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20400437) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10200219 + 10200220.

It is an arithmetic number, because the mean of its divisors is an integer number (10200220).

Almost surely, 2^20400439 is an apocalyptic number.

20400439 is a deficient number, since it is larger than the sum of its proper divisors (1).

20400439 is an equidigital number, since it uses as much as digits as its factorization.

20400439 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 864, while the sum is 22.

The square root of 20400439 is about 4516.6845141099. The cubic root of 20400439 is about 273.2414015973.

The spelling of 20400439 in words is "twenty million, four hundred thousand, four hundred thirty-nine".