21473988 has 12 divisors (see below), whose sum is σ = 50106000. Its totient is φ = 7157992.

The previous prime is 21473987. The next prime is 21474031. The reversal of 21473988 is 88937412.

It is a tau number, because it is divible by the number of its divisors (12).

It is a super-2 number, since 2×21473988² = 922264321248288, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21473987) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 894738 + ... + 894761.

It is an arithmetic number, because the mean of its divisors is an integer number (4175500).

Almost surely, 2^21473988 is an apocalyptic number.

It is an amenable number.

21473988 is an abundant number, since it is smaller than the sum of its proper divisors (28632012).

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

21473988 is a wasteful number, since it uses less digits than its factorization.

21473988 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1789506 (or 1789504 counting only the distinct ones).

The product of its digits is 96768, while the sum is 42.

The square root of 21473988 is about 4634.0034527393. The cubic root of 21473988 is about 277.9527031661.

The spelling of 21473988 in words is "twenty-one million, four hundred seventy-three thousand, nine hundred eighty-eight".