21691219 has 8 divisors (see below), whose sum is σ = 23851008. Its totient is φ = 19562760.

The previous prime is 21691207. The next prime is 21691223. The reversal of 21691219 is 91219612.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21691219 - 2⁹ = 21690707 is a prime.

It is a super-2 number, since 2×21691219² = 941017963411922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21691249) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6367 + ... + 9160.

It is an arithmetic number, because the mean of its divisors is an integer number (2981376).

Almost surely, 2^21691219 is an apocalyptic number.

21691219 is a deficient number, since it is larger than the sum of its proper divisors (2159789).

21691219 is a wasteful number, since it uses less digits than its factorization.

21691219 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15665.

The product of its digits is 1944, while the sum is 31.

The square root of 21691219 is about 4657.3832781939. The cubic root of 21691219 is about 278.8868174837.

The spelling of 21691219 in words is "twenty-one million, six hundred ninety-one thousand, two hundred nineteen".