21751897 has 4 divisors (see below), whose sum is σ = 21766096. Its totient is φ = 21737700.

The previous prime is 21751843. The next prime is 21751913. The reversal of 21751897 is 79815712.

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.

It is a cyclic number.

It is not a de Polignac number, because 21751897 - 2¹⁵ = 21719129 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21751817) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4479 + ... + 7972.

It is an arithmetic number, because the mean of its divisors is an integer number (5441524).

Almost surely, 2^21751897 is an apocalyptic number.

It is an amenable number.

21751897 is a deficient number, since it is larger than the sum of its proper divisors (14199).

21751897 is a wasteful number, since it uses less digits than its factorization.

21751897 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14198.

The product of its digits is 35280, while the sum is 40.

The square root of 21751897 is about 4663.8929018578. The cubic root of 21751897 is about 279.1466236842.

The spelling of 21751897 in words is "twenty-one million, seven hundred fifty-one thousand, eight hundred ninety-seven".