21953597 has 4 divisors (see below), whose sum is σ = 21962976. Its totient is φ = 21944220.

The previous prime is 21953587. The next prime is 21953621. The reversal of 21953597 is 79535912.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 21953597 - 2¹⁰ = 21952573 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21953537) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2072 + ... + 6942.

It is an arithmetic number, because the mean of its divisors is an integer number (5490744).

Almost surely, 2^21953597 is an apocalyptic number.

It is an amenable number.

21953597 is a deficient number, since it is larger than the sum of its proper divisors (9379).

21953597 is an equidigital number, since it uses as much as digits as its factorization.

21953597 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9378.

The product of its digits is 85050, while the sum is 41.

The square root of 21953597 is about 4685.4665722850. The cubic root of 21953597 is about 280.0067898013.

The spelling of 21953597 in words is "twenty-one million, nine hundred fifty-three thousand, five hundred ninety-seven".