21471984 has 30 divisors (see below), whose sum is σ = 60092136. Its totient is φ = 7157280.

The previous prime is 21471979. The next prime is 21471991. The reversal of 21471984 is 48917412.

It is a super-2 number, since 2×21471984² = 922092193792512, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 74412 + ... + 74699.

Almost surely, 2^21471984 is an apocalyptic number.

21471984 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21471984 is an abundant number, since it is smaller than the sum of its proper divisors (38620152).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21471984 is a wasteful number, since it uses less digits than its factorization.

21471984 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 149125 (or 149116 counting only the distinct ones).

The product of its digits is 16128, while the sum is 36.

The square root of 21471984 is about 4633.7872199746. The cubic root of 21471984 is about 277.9440565103.

The spelling of 21471984 in words is "twenty-one million, four hundred seventy-one thousand, nine hundred eighty-four".