20997619 has 2 divisors, whose sum is σ = 20997620. Its totient is φ = 20997618.

The previous prime is 20997583. The next prime is 20997637. The reversal of 20997619 is 91679902.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20997619 - 2⁷ = 20997491 is a prime.

It is a super-2 number, since 2×20997619² = 881800007338322, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (20997649) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10498809 + 10498810.

It is an arithmetic number, because the mean of its divisors is an integer number (10498810).

Almost surely, 2^20997619 is an apocalyptic number.

20997619 is a deficient number, since it is larger than the sum of its proper divisors (1).

20997619 is an equidigital number, since it uses as much as digits as its factorization.

20997619 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 61236, while the sum is 43.

The square root of 20997619 is about 4582.3158991933. The cubic root of 20997619 is about 275.8819902623.

The spelling of 20997619 in words is "twenty million, nine hundred ninety-seven thousand, six hundred nineteen".