21499811 has 4 divisors (see below), whose sum is σ = 22631400. Its totient is φ = 20368224.

The previous prime is 21499801. The next prime is 21499813. The reversal of 21499811 is 11899412.

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-21499811 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21499813) 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 3 ways as a sum of consecutive naturals, for example, 565766 + ... + 565803.

It is an arithmetic number, because the mean of its divisors is an integer number (5657850).

Almost surely, 2^21499811 is an apocalyptic number.

21499811 is a deficient number, since it is larger than the sum of its proper divisors (1131589).

21499811 is a wasteful number, since it uses less digits than its factorization.

21499811 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1131588.

The product of its digits is 5184, while the sum is 35.

The square root of 21499811 is about 4636.7888673089. The cubic root of 21499811 is about 278.0640735289.

The spelling of 21499811 in words is "twenty-one million, four hundred ninety-nine thousand, eight hundred eleven".