21474864 has 120 divisors (see below), whose sum is σ = 64995840. Its totient is φ = 6597504.

The previous prime is 21474851. The next prime is 21474913. The reversal of 21474864 is 46847412.

It is a super-2 number, since 2×21474864² = 922339567636992, 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 23 ways as a sum of consecutive naturals, for example, 128509 + ... + 128675.

It is an arithmetic number, because the mean of its divisors is an integer number (541632).

Almost surely, 2^21474864 is an apocalyptic number.

21474864 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21474864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32497920).

21474864 is an abundant number, since it is smaller than the sum of its proper divisors (43520976).

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

21474864 is a wasteful number, since it uses less digits than its factorization.

21474864 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 247 (or 238 counting only the distinct ones).

The product of its digits is 43008, while the sum is 36.

The square root of 21474864 is about 4634.0979704793. The cubic root of 21474864 is about 277.9564826729.

It can be divided in two parts, 214 and 74864, that added together give a triangular number (75078 = T₃₈₇).

The spelling of 21474864 in words is "twenty-one million, four hundred seventy-four thousand, eight hundred sixty-four".