21480191 has 4 divisors (see below), whose sum is σ = 21535800. Its totient is φ = 21424584.

The previous prime is 21480181. The next prime is 21480209. The reversal of 21480191 is 19108412.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21480191 is a prime.

It is a super-2 number, since 2×21480191² = 922797210792962, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21480191.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21480101) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 27221 + ... + 27998.

It is an arithmetic number, because the mean of its divisors is an integer number (5383950).

Almost surely, 2^21480191 is an apocalyptic number.

21480191 is a deficient number, since it is larger than the sum of its proper divisors (55609).

21480191 is an equidigital number, since it uses as much as digits as its factorization.

21480191 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 55608.

The product of its (nonzero) digits is 576, while the sum is 26.

The square root of 21480191 is about 4634.6726961027. The cubic root of 21480191 is about 277.9794638316.

It can be divided in two parts, 21480 and 191, that multiplied together give a triangular number (4102680 = T₂₈₆₄).

The spelling of 21480191 in words is "twenty-one million, four hundred eighty thousand, one hundred ninety-one".