21719811 has 16 divisors (see below), whose sum is σ = 30080160. Its totient is φ = 13923840.

The previous prime is 21719807. The next prime is 21719813. The reversal of 21719811 is 11891712.

It is not a de Polignac number, because 21719811 - 2² = 21719807 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21719813) 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, 36331 + ... + 36923.

It is an arithmetic number, because the mean of its divisors is an integer number (1880010).

Almost surely, 2^21719811 is an apocalyptic number.

21719811 is a deficient number, since it is larger than the sum of its proper divisors (8360349).

21719811 is a wasteful number, since it uses less digits than its factorization.

21719811 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1046.

The product of its digits is 1008, while the sum is 30.

The square root of 21719811 is about 4660.4518021325. The cubic root of 21719811 is about 279.0093007010.

The spelling of 21719811 in words is "twenty-one million, seven hundred nineteen thousand, eight hundred eleven".