21022497 has 10 divisors (see below), whose sum is σ = 31404098. Its totient is φ = 14014944.

The previous prime is 21022471. The next prime is 21022517. The reversal of 21022497 is 79422012.

It can be written as a sum of positive squares in only one way, i.e., 18974736 + 2047761 = 4356^2 + 1431^2 .

It is not a de Polignac number, because 21022497 - 2¹² = 21018401 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21022497.

It is not an unprimeable number, because it can be changed into a prime (21022427) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 129688 + ... + 129849.

Almost surely, 2^21022497 is an apocalyptic number.

21022497 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

It is an amenable number.

21022497 is a deficient number, since it is larger than the sum of its proper divisors (10381601).

21022497 is an equidigital number, since it uses as much as digits as its factorization.

21022497 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 259549 (or 259540 counting only the distinct ones).

The product of its (nonzero) digits is 2016, while the sum is 27.

The square root of 21022497 is about 4585.0296618452. The cubic root of 21022497 is about 275.9909023466.

The spelling of 21022497 in words is "twenty-one million, twenty-two thousand, four hundred ninety-seven".