21497472 has 48 divisors (see below), whose sum is σ = 61864530. Its totient is φ = 7165440.

The previous prime is 21497467. The next prime is 21497473. The reversal of 21497472 is 27479412.

It can be written as a sum of positive squares in only one way, i.e., 21013056 + 484416 = 4584^2 + 696^2 .

It is a tau number, because it is divible by the number of its divisors (48).

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

It is a zygodrome in base 3.

It is not an unprimeable number, because it can be changed into a prime (21497473) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 8179 + ... + 10482.

Almost surely, 2^21497472 is an apocalyptic number.

It is an amenable number.

21497472 is an abundant number, since it is smaller than the sum of its proper divisors (40367058).

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

21497472 is a wasteful number, since it uses less digits than its factorization.

21497472 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18681 (or 18666 counting only the distinct ones).

The product of its digits is 28224, while the sum is 36.

The square root of 21497472 is about 4636.5366384835. The cubic root of 21497472 is about 278.0539894797.

The spelling of 21497472 in words is "twenty-one million, four hundred ninety-seven thousand, four hundred seventy-two".