21752497 has 8 divisors (see below), whose sum is σ = 23566760. Its totient is φ = 20077200.

The previous prime is 21752461. The next prime is 21752519. The reversal of 21752497 is 79425712.

It can be written as a sum of positive squares in 4 ways, for example, as 1825201 + 19927296 = 1351^2 + 4464^2 .

It is not a de Polignac number, because 21752497 - 2⁷ = 21752369 is a prime.

It is a super-2 number, since 2×21752497² = 946342251470018, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21752447) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2754 + ... + 7147.

It is an arithmetic number, because the mean of its divisors is an integer number (2945845).

Almost surely, 2^21752497 is an apocalyptic number.

It is an amenable number.

21752497 is a deficient number, since it is larger than the sum of its proper divisors (1814263).

21752497 is an frugal number, since it uses more digits than its factorization.

21752497 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9940 (or 9914 counting only the distinct ones).

The product of its digits is 35280, while the sum is 37.

The square root of 21752497 is about 4663.9572253613. The cubic root of 21752497 is about 279.1491903022.

The spelling of 21752497 in words is "twenty-one million, seven hundred fifty-two thousand, four hundred ninety-seven".