21539419 has 8 divisors (see below), whose sum is σ = 23532912. Its totient is φ = 19551840.

The previous prime is 21539417. The next prime is 21539449. The reversal of 21539419 is 91493512.

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

It is not a de Polignac number, because 21539419 - 2¹ = 21539417 is a prime.

It is a super-2 number, since 2×21539419² = 927893141715122, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21539411) 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, 10177 + ... + 12109.

It is an arithmetic number, because the mean of its divisors is an integer number (2941614).

Almost surely, 2^21539419 is an apocalyptic number.

21539419 is a deficient number, since it is larger than the sum of its proper divisors (1993493).

21539419 is a wasteful number, since it uses less digits than its factorization.

21539419 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2957.

The product of its digits is 9720, while the sum is 34.

The square root of 21539419 is about 4641.0579612843. The cubic root of 21539419 is about 278.2347231763.

The spelling of 21539419 in words is "twenty-one million, five hundred thirty-nine thousand, four hundred nineteen".