21471788 has 36 divisors (see below), whose sum is σ = 42488208. Its totient is φ = 9472320.

The previous prime is 21471787. The next prime is 21471839. The reversal of 21471788 is 88717412.

It is a super-2 number, since 2×21471788² = 922075359833888, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21471781) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 14858 + ... + 16238.

It is an arithmetic number, because the mean of its divisors is an integer number (1180228).

Almost surely, 2^21471788 is an apocalyptic number.

It is an amenable number.

21471788 is a deficient number, since it is larger than the sum of its proper divisors (21016420).

21471788 is a wasteful number, since it uses less digits than its factorization.

21471788 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1434 (or 1419 counting only the distinct ones).

The product of its digits is 25088, while the sum is 38.

The square root of 21471788 is about 4633.7660709190. The cubic root of 21471788 is about 277.9432108005.

The spelling of 21471788 in words is "twenty-one million, four hundred seventy-one thousand, seven hundred eighty-eight".