21751473 has 4 divisors (see below), whose sum is σ = 29001968. Its totient is φ = 14500980.

The previous prime is 21751469. The next prime is 21751481. The reversal of 21751473 is 37415712.

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 not a de Polignac number, because 21751473 - 2² = 21751469 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21751473.

It is not an unprimeable number, because it can be changed into a prime (21751403) 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, 3625243 + ... + 3625248.

It is an arithmetic number, because the mean of its divisors is an integer number (7250492).

Almost surely, 2^21751473 is an apocalyptic number.

It is an amenable number.

21751473 is a deficient number, since it is larger than the sum of its proper divisors (7250495).

21751473 is an equidigital number, since it uses as much as digits as its factorization.

21751473 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7250494.

The product of its digits is 5880, while the sum is 30.

The square root of 21751473 is about 4663.8474460471. The cubic root of 21751473 is about 279.1448099123.

The spelling of 21751473 in words is "twenty-one million, seven hundred fifty-one thousand, four hundred seventy-three".