21751001 has 4 divisors (see below), whose sum is σ = 21814032. Its totient is φ = 21687972.

The previous prime is 21750997. The next prime is 21751019. The reversal of 21751001 is 10015712.

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 21751001 - 2² = 21750997 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21751021) 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, 30995 + ... + 31688.

It is an arithmetic number, because the mean of its divisors is an integer number (5453508).

Almost surely, 2^21751001 is an apocalyptic number.

It is an amenable number.

21751001 is a deficient number, since it is larger than the sum of its proper divisors (63031).

21751001 is an equidigital number, since it uses as much as digits as its factorization.

21751001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 63030.

The product of its (nonzero) digits is 70, while the sum is 17.

The square root of 21751001 is about 4663.7968437744. The cubic root of 21751001 is about 279.1427907800.

Adding to 21751001 its reverse (10015712), we get a palindrome (31766713).

The spelling of 21751001 in words is "twenty-one million, seven hundred fifty-one thousand, one".