21872797 has 2 divisors, whose sum is σ = 21872798. Its totient is φ = 21872796.

The previous prime is 21872789. The next prime is 21872801. The reversal of 21872797 is 79727812.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20693401 + 1179396 = 4549^2 + 1086^2 .

It is a cyclic number.

It is not a de Polignac number, because 21872797 - 2³ = 21872789 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21872737) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10936398 + 10936399.

It is an arithmetic number, because the mean of its divisors is an integer number (10936399).

Almost surely, 2^21872797 is an apocalyptic number.

It is an amenable number.

21872797 is a deficient number, since it is larger than the sum of its proper divisors (1).

21872797 is an equidigital number, since it uses as much as digits as its factorization.

21872797 is an evil number, because the sum of its binary digits is even.

The product of its digits is 98784, while the sum is 43.

The square root of 21872797 is about 4676.8362169313. The cubic root of 21872797 is about 279.6628467414.

The spelling of 21872797 in words is "twenty-one million, eight hundred seventy-two thousand, seven hundred ninety-seven".