21881351 has 2 divisors, whose sum is σ = 21881352. Its totient is φ = 21881350.

The previous prime is 21881297. The next prime is 21881359. The reversal of 21881351 is 15318812.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21881351 - 2⁶ = 21881287 is a prime.

It is equal to p_1382195 and since 21881351 and 1382195 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21881359) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10940675 + 10940676.

It is an arithmetic number, because the mean of its divisors is an integer number (10940676).

Almost surely, 2^21881351 is an apocalyptic number.

21881351 is a deficient number, since it is larger than the sum of its proper divisors (1).

21881351 is an equidigital number, since it uses as much as digits as its factorization.

21881351 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1920, while the sum is 29.

The square root of 21881351 is about 4677.7506346534. The cubic root of 21881351 is about 279.6992987813.

The spelling of 21881351 in words is "twenty-one million, eight hundred eighty-one thousand, three hundred fifty-one".