21455291 has 16 divisors (see below), whose sum is σ = 25643520. Its totient is φ = 17692320.

The previous prime is 21455281. The next prime is 21455293. The reversal of 21455291 is 19255412.

It is a cyclic number.

It is not a de Polignac number, because 21455291 - 2¹⁸ = 21193147 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21455293) 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, 7166 + ... + 9708.

It is an arithmetic number, because the mean of its divisors is an integer number (1602720).

Almost surely, 2^21455291 is an apocalyptic number.

21455291 is a deficient number, since it is larger than the sum of its proper divisors (4188229).

21455291 is a wasteful number, since it uses less digits than its factorization.

21455291 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2626.

The product of its digits is 3600, while the sum is 29.

The square root of 21455291 is about 4631.9856433284. The cubic root of 21455291 is about 277.8720103344.

The spelling of 21455291 in words is "twenty-one million, four hundred fifty-five thousand, two hundred ninety-one".