21494664 has 72 divisors (see below), whose sum is σ = 61900410. Its totient is φ = 6736896.

The previous prime is 21494663. The next prime is 21494677. The reversal of 21494664 is 46649412.

It can be written as a sum of positive squares in 3 ways, for example, as 20629764 + 864900 = 4542^2 + 930^2 .

It is a tau number, because it is divible by the number of its divisors (72).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a nude number because it is divisible by every one of its digits.

It is not an unprimeable number, because it can be changed into a prime (21494663) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 20292 + ... + 21324.

Almost surely, 2^21494664 is an apocalyptic number.

21494664 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 21494664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30950205).

21494664 is an abundant number, since it is smaller than the sum of its proper divisors (40405746).

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

21494664 is a wasteful number, since it uses less digits than its factorization.

21494664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1079 (or 1055 counting only the distinct ones).

The product of its digits is 41472, while the sum is 36.

The square root of 21494664 is about 4636.2338163643. The cubic root of 21494664 is about 278.0418824809.

The spelling of 21494664 in words is "twenty-one million, four hundred ninety-four thousand, six hundred sixty-four".