21345870 has 96 divisors (see below), whose sum is σ = 64235808. Its totient is φ = 4499712.

The previous prime is 21345853. The next prime is 21345881. The reversal of 21345870 is 7854312.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 18552 + ... + 19668.

It is an arithmetic number, because the mean of its divisors is an integer number (669123).

Almost surely, 2^21345870 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21345870, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32117904).

21345870 is an abundant number, since it is smaller than the sum of its proper divisors (42889938).

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

21345870 is a wasteful number, since it uses less digits than its factorization.

21345870 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1154 (or 1147 counting only the distinct ones).

The product of its (nonzero) digits is 6720, while the sum is 30.

The square root of 21345870 is about 4620.1590881700. The cubic root of 21345870 is about 277.3988268466.

The spelling of 21345870 in words is "twenty-one million, three hundred forty-five thousand, eight hundred seventy".