20731397 has 2 divisors, whose sum is σ = 20731398. Its totient is φ = 20731396.

The previous prime is 20731391. The next prime is 20731409. The reversal of 20731397 is 79313702.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16924996 + 3806401 = 4114^2 + 1951^2 .

It is a cyclic number.

It is not a de Polignac number, because 20731397 - 2¹⁰ = 20730373 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20731391) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10365698 + 10365699.

It is an arithmetic number, because the mean of its divisors is an integer number (10365699).

Almost surely, 2^20731397 is an apocalyptic number.

It is an amenable number.

20731397 is a deficient number, since it is larger than the sum of its proper divisors (1).

20731397 is an equidigital number, since it uses as much as digits as its factorization.

20731397 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 7938, while the sum is 32.

The square root of 20731397 is about 4553.1743871721. The cubic root of 20731397 is about 274.7110883147.

The spelling of 20731397 in words is "twenty million, seven hundred thirty-one thousand, three hundred ninety-seven".