21872371 has 2 divisors, whose sum is σ = 21872372. Its totient is φ = 21872370.

The previous prime is 21872369. The next prime is 21872377. The reversal of 21872371 is 17327812.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21872371 - 2¹ = 21872369 is a prime.

It is a super-2 number, since 2×21872371² = 956801226323282, which contains 22 as substring.

Together with 21872369, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21872377) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10936185 + 10936186.

It is an arithmetic number, because the mean of its divisors is an integer number (10936186).

Almost surely, 2^21872371 is an apocalyptic number.

21872371 is a deficient number, since it is larger than the sum of its proper divisors (1).

21872371 is an equidigital number, since it uses as much as digits as its factorization.

21872371 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4704, while the sum is 31.

The square root of 21872371 is about 4676.7906731005. The cubic root of 21872371 is about 279.6610311354.

The spelling of 21872371 in words is "twenty-one million, eight hundred seventy-two thousand, three hundred seventy-one".