20400997 has 2 divisors, whose sum is σ = 20400998. Its totient is φ = 20400996.

The previous prime is 20400967. The next prime is 20401001. The reversal of 20400997 is 79900402.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17986081 + 2414916 = 4241^2 + 1554^2 .

It is a cyclic number.

It is not a de Polignac number, because 20400997 - 2⁷ = 20400869 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20400967) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10200498 + 10200499.

It is an arithmetic number, because the mean of its divisors is an integer number (10200499).

Almost surely, 2^20400997 is an apocalyptic number.

It is an amenable number.

20400997 is a deficient number, since it is larger than the sum of its proper divisors (1).

20400997 is an equidigital number, since it uses as much as digits as its factorization.

20400997 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4536, while the sum is 31.

The square root of 20400997 is about 4516.7462846611. The cubic root of 20400997 is about 273.2438928396.

The spelling of 20400997 in words is "twenty million, four hundred thousand, nine hundred ninety-seven".