21751449 has 16 divisors (see below), whose sum is σ = 31540608. Its totient is φ = 13277952.

The previous prime is 21751427. The next prime is 21751469. The reversal of 21751449 is 94415712.

It is a happy number.

It is not a de Polignac number, because 21751449 - 2⁸ = 21751193 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21751469) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3877 + ... + 7650.

It is an arithmetic number, because the mean of its divisors is an integer number (1971288).

Almost surely, 2^21751449 is an apocalyptic number.

It is an amenable number.

21751449 is a deficient number, since it is larger than the sum of its proper divisors (9789159).

21751449 is a wasteful number, since it uses less digits than its factorization.

21751449 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11584.

The product of its digits is 10080, while the sum is 33.

The square root of 21751449 is about 4663.8448730634. The cubic root of 21751449 is about 279.1447072453.

The spelling of 21751449 in words is "twenty-one million, seven hundred fifty-one thousand, four hundred forty-nine".