21890497 has 2 divisors, whose sum is σ = 21890498. Its totient is φ = 21890496.

The previous prime is 21890467. The next prime is 21890513. The reversal of 21890497 is 79409812.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21566736 + 323761 = 4644^2 + 569^2 .

It is a cyclic number.

It is not a de Polignac number, because 21890497 - 2⁷ = 21890369 is a prime.

It is not a weakly prime, because it can be changed into another prime (21890417) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10945248 + 10945249.

It is an arithmetic number, because the mean of its divisors is an integer number (10945249).

Almost surely, 2^21890497 is an apocalyptic number.

It is an amenable number.

21890497 is a deficient number, since it is larger than the sum of its proper divisors (1).

21890497 is an equidigital number, since it uses as much as digits as its factorization.

21890497 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 36288, while the sum is 40.

The square root of 21890497 is about 4678.7281391421. The cubic root of 21890497 is about 279.7382630642.

The spelling of 21890497 in words is "twenty-one million, eight hundred ninety thousand, four hundred ninety-seven".