21671020 has 48 divisors (see below), whose sum is σ = 54754560. Its totient is φ = 7038144.

The previous prime is 21671017. The next prime is 21671047. The reversal of 21671020 is 2017612.

It is a Harshad number since it is a multiple of its sum of digits (19).

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1414 + ... + 6733.

It is an arithmetic number, because the mean of its divisors is an integer number (1140720).

Almost surely, 2^21671020 is an apocalyptic number.

21671020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21671020 is an abundant number, since it is smaller than the sum of its proper divisors (33083540).

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

21671020 is a wasteful number, since it uses less digits than its factorization.

21671020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8182 (or 8180 counting only the distinct ones).

The product of its (nonzero) digits is 168, while the sum is 19.

The square root of 21671020 is about 4655.2142807824. The cubic root of 21671020 is about 278.8002235445.

Adding to 21671020 its reverse (2017612), we get a palindrome (23688632).

The spelling of 21671020 in words is "twenty-one million, six hundred seventy-one thousand, twenty".