21751151 has 4 divisors (see below), whose sum is σ = 21842400. Its totient is φ = 21659904.

The previous prime is 21751139. The next prime is 21751157. The reversal of 21751151 is 15115712.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21751151 - 2⁶ = 21751087 is a prime.

It is a super-2 number, since 2×21751151² = 946225139649602, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21751157) 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, 45266 + ... + 45743.

It is an arithmetic number, because the mean of its divisors is an integer number (5460600).

Almost surely, 2^21751151 is an apocalyptic number.

21751151 is a deficient number, since it is larger than the sum of its proper divisors (91249).

21751151 is an equidigital number, since it uses as much as digits as its factorization.

21751151 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 91248.

The product of its digits is 350, while the sum is 23.

The square root of 21751151 is about 4663.8129250646. The cubic root of 21751151 is about 279.1434324566.

Adding to 21751151 its reverse (15115712), we get a palindrome (36866863).

The spelling of 21751151 in words is "twenty-one million, seven hundred fifty-one thousand, one hundred fifty-one".