21255351 has 16 divisors (see below), whose sum is σ = 30621696. Its totient is φ = 13036896.

The previous prime is 21255329. The next prime is 21255361. The reversal of 21255351 is 15355212.

It is a happy number.

It is not a de Polignac number, because 21255351 - 2⁹ = 21254839 is a prime.

It is a super-2 number, since 2×21255351² = 903579892266402, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21255301) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 14226 + ... + 15648.

It is an arithmetic number, because the mean of its divisors is an integer number (1913856).

Almost surely, 2^21255351 is an apocalyptic number.

21255351 is a deficient number, since it is larger than the sum of its proper divisors (9366345).

21255351 is a wasteful number, since it uses less digits than its factorization.

21255351 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1822.

The product of its digits is 1500, while the sum is 24.

The square root of 21255351 is about 4610.3525895532. The cubic root of 21255351 is about 277.0061600719.

The spelling of 21255351 in words is "twenty-one million, two hundred fifty-five thousand, three hundred fifty-one".