21623919 has 16 divisors (see below), whose sum is σ = 30670080. Its totient is φ = 13512960.

The previous prime is 21623911. The next prime is 21623939. The reversal of 21623919 is 91932612.

It is not a de Polignac number, because 21623919 - 2³ = 21623911 is a prime.

It is a super-3 number, since 3×21623919³ (a number of 23 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a self number, because there is not a number n which added to its sum of digits gives 21623919.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21623911) 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, 3574 + ... + 7484.

It is an arithmetic number, because the mean of its divisors is an integer number (1916880).

Almost surely, 2^21623919 is an apocalyptic number.

21623919 is a deficient number, since it is larger than the sum of its proper divisors (9046161).

21623919 is a wasteful number, since it uses less digits than its factorization.

21623919 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4030.

The product of its digits is 5832, while the sum is 33.

The square root of 21623919 is about 4650.1525781419. The cubic root of 21623919 is about 278.5980903945.

The spelling of 21623919 in words is "twenty-one million, six hundred twenty-three thousand, nine hundred nineteen".