20997407 has 2 divisors, whose sum is σ = 20997408. Its totient is φ = 20997406.

The previous prime is 20997377. The next prime is 20997419. The reversal of 20997407 is 70479902.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20997407 is a prime.

It is a super-2 number, since 2×20997407² = 881782201447298, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20997437) 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, 10498703 + 10498704.

It is an arithmetic number, because the mean of its divisors is an integer number (10498704).

Almost surely, 2^20997407 is an apocalyptic number.

20997407 is a deficient number, since it is larger than the sum of its proper divisors (1).

20997407 is an equidigital number, since it uses as much as digits as its factorization.

20997407 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 31752, while the sum is 38.

The square root of 20997407 is about 4582.2927667272. The cubic root of 20997407 is about 275.8810617891.

The spelling of 20997407 in words is "twenty million, nine hundred ninety-seven thousand, four hundred seven".