20451397 has 2 divisors, whose sum is σ = 20451398. Its totient is φ = 20451396.

The previous prime is 20451373. The next prime is 20451407. The reversal of 20451397 is 79315402.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17715681 + 2735716 = 4209^2 + 1654^2 .

It is a cyclic number.

It is not a de Polignac number, because 20451397 - 2¹⁹ = 19927109 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20451317) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10225698 + 10225699.

It is an arithmetic number, because the mean of its divisors is an integer number (10225699).

Almost surely, 2^20451397 is an apocalyptic number.

It is an amenable number.

20451397 is a deficient number, since it is larger than the sum of its proper divisors (1).

20451397 is an equidigital number, since it uses as much as digits as its factorization.

20451397 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 7560, while the sum is 31.

The square root of 20451397 is about 4522.3220805246. The cubic root of 20451397 is about 273.4687211828.

Adding to 20451397 its reverse (79315402), we get a palindrome (99766799).

The spelling of 20451397 in words is "twenty million, four hundred fifty-one thousand, three hundred ninety-seven".