21542597 has 2 divisors, whose sum is σ = 21542598. Its totient is φ = 21542596.

The previous prime is 21542579. The next prime is 21542623. The reversal of 21542597 is 79524512.

Together with previous prime (21542579) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18395521 + 3147076 = 4289^2 + 1774^2 .

It is a cyclic number.

It is not a de Polignac number, because 21542597 - 2⁸ = 21542341 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21542537) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10771298 + 10771299.

It is an arithmetic number, because the mean of its divisors is an integer number (10771299).

Almost surely, 2^21542597 is an apocalyptic number.

It is an amenable number.

21542597 is a deficient number, since it is larger than the sum of its proper divisors (1).

21542597 is an equidigital number, since it uses as much as digits as its factorization.

21542597 is an evil number, because the sum of its binary digits is even.

The product of its digits is 25200, while the sum is 35.

The square root of 21542597 is about 4641.4003274874. The cubic root of 21542597 is about 278.2484064062.

The spelling of 21542597 in words is "twenty-one million, five hundred forty-two thousand, five hundred ninety-seven".