21471999 has 8 divisors (see below), whose sum is σ = 28750080. Its totient is φ = 14254296.

The previous prime is 21471991. The next prime is 21472021. The reversal of 21471999 is 99917412.

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

It is not a de Polignac number, because 21471999 - 2³ = 21471991 is a prime.

It is a super-2 number, since 2×21471999² = 922093482112002, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21471999.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21471991) 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, 14257 + ... + 15690.

It is an arithmetic number, because the mean of its divisors is an integer number (3593760).

Almost surely, 2^21471999 is an apocalyptic number.

21471999 is a deficient number, since it is larger than the sum of its proper divisors (7278081).

21471999 is a wasteful number, since it uses less digits than its factorization.

21471999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30189.

The product of its digits is 40824, while the sum is 42.

The square root of 21471999 is about 4633.7888385208. The cubic root of 21471999 is about 277.9441212328.

The spelling of 21471999 in words is "twenty-one million, four hundred seventy-one thousand, nine hundred ninety-nine".