20499971 has 2 divisors, whose sum is σ = 20499972. Its totient is φ = 20499970.

The previous prime is 20499967. The next prime is 20500019. The reversal of 20499971 is 17999402.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20499971 - 2² = 20499967 is a prime.

It is a super-2 number, since 2×20499971² = 840497622001682, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (20499071) 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, 10249985 + 10249986.

It is an arithmetic number, because the mean of its divisors is an integer number (10249986).

Almost surely, 2^20499971 is an apocalyptic number.

20499971 is a deficient number, since it is larger than the sum of its proper divisors (1).

20499971 is an equidigital number, since it uses as much as digits as its factorization.

20499971 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 40824, while the sum is 41.

The square root of 20499971 is about 4527.6893665533. The cubic root of 20499971 is about 273.6850546851.

The spelling of 20499971 in words is "twenty million, four hundred ninety-nine thousand, nine hundred seventy-one".