21908797 has 2 divisors, whose sum is σ = 21908798. Its totient is φ = 21908796.

The previous prime is 21908791. The next prime is 21908827. The reversal of 21908797 is 79780912.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13111641 + 8797156 = 3621^2 + 2966^2 .

It is a cyclic number.

It is not a de Polignac number, because 21908797 - 2¹⁹ = 21384509 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21908791) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10954398 + 10954399.

It is an arithmetic number, because the mean of its divisors is an integer number (10954399).

Almost surely, 2^21908797 is an apocalyptic number.

It is an amenable number.

21908797 is a deficient number, since it is larger than the sum of its proper divisors (1).

21908797 is an equidigital number, since it uses as much as digits as its factorization.

21908797 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 63504, while the sum is 43.

The square root of 21908797 is about 4680.6833902754. The cubic root of 21908797 is about 279.8161931413.

The spelling of 21908797 in words is "twenty-one million, nine hundred eight thousand, seven hundred ninety-seven".