21906919 has 8 divisors (see below), whose sum is σ = 22743360. Its totient is φ = 21075936.

The previous prime is 21906917. The next prime is 21906949. The reversal of 21906919 is 91960912.

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 21906919 - 2¹ = 21906917 is a prime.

It is a super-2 number, since 2×21906919² = 959826200145122, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21906917) 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, 8002 + ... + 10384.

It is an arithmetic number, because the mean of its divisors is an integer number (2842920).

Almost surely, 2^21906919 is an apocalyptic number.

21906919 is a gapful number since it is divisible by the number (29) formed by its first and last digit.

21906919 is a deficient number, since it is larger than the sum of its proper divisors (836441).

21906919 is a wasteful number, since it uses less digits than its factorization.

21906919 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2729.

The product of its (nonzero) digits is 8748, while the sum is 37.

The square root of 21906919 is about 4680.4827742446. The cubic root of 21906919 is about 279.8081977255.

The spelling of 21906919 in words is "twenty-one million, nine hundred six thousand, nine hundred nineteen".