21357897 has 8 divisors (see below), whose sum is σ = 31066080. Its totient is φ = 12944160.

The previous prime is 21357871. The next prime is 21357901. The reversal of 21357897 is 79875312.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21357897 - 2¹⁰ = 21356873 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21357827) 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, 323572 + ... + 323637.

It is an arithmetic number, because the mean of its divisors is an integer number (3883260).

Almost surely, 2^21357897 is an apocalyptic number.

It is an amenable number.

21357897 is a deficient number, since it is larger than the sum of its proper divisors (9708183).

21357897 is a wasteful number, since it uses less digits than its factorization.

21357897 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 647223.

The product of its digits is 105840, while the sum is 42.

The square root of 21357897 is about 4621.4604834403. The cubic root of 21357897 is about 277.4509157564.

The spelling of 21357897 in words is "twenty-one million, three hundred fifty-seven thousand, eight hundred ninety-seven".