21366351 has 12 divisors (see below), whose sum is σ = 30909112. Its totient is φ = 14222736.

The previous prime is 21366343. The next prime is 21366377. The reversal of 21366351 is 15366312.

21366351 is a `hidden beast` number, since 21 + 3 + 6 + 635 + 1 = 666.

It is not a de Polignac number, because 21366351 - 2³ = 21366343 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21366311) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 6540 + ... + 9246.

Almost surely, 2^21366351 is an apocalyptic number.

21366351 is a deficient number, since it is larger than the sum of its proper divisors (9542761).

21366351 is a wasteful number, since it uses less digits than its factorization.

21366351 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3590 (or 3587 counting only the distinct ones).

The product of its digits is 3240, while the sum is 27.

The square root of 21366351 is about 4622.3750388734. The cubic root of 21366351 is about 277.4875183088.

It can be divided in two parts, 213 and 66351, that added together give a square (66564 = 258²).

The spelling of 21366351 in words is "twenty-one million, three hundred sixty-six thousand, three hundred fifty-one".