20400001 has 4 divisors (see below), whose sum is σ = 20897604. Its totient is φ = 19902400.

The previous prime is 20399993. The next prime is 20400013. The reversal of 20400001 is 10000402.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 10000402 = 2 ⋅5000201.

It can be written as a sum of positive squares in 2 ways, for example, as 1703025 + 18696976 = 1305^2 + 4324^2 .

It is a cyclic number.

It is not a de Polignac number, because 20400001 - 2³ = 20399993 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20400031) 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, 248740 + ... + 248821.

It is an arithmetic number, because the mean of its divisors is an integer number (5224401).

Almost surely, 2^20400001 is an apocalyptic number.

It is an amenable number.

20400001 is a deficient number, since it is larger than the sum of its proper divisors (497603).

20400001 is an equidigital number, since it uses as much as digits as its factorization.

20400001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 497602.

The product of its (nonzero) digits is 8, while the sum is 7.

The square root of 20400001 is about 4516.6360269563. The cubic root of 20400001 is about 273.2394460741.

Adding to 20400001 its reverse (10000402), we get a palindrome (30400403).

The spelling of 20400001 in words is "twenty million, four hundred thousand, one".