21499501 has 2 divisors, whose sum is σ = 21499502. Its totient is φ = 21499500.

The previous prime is 21499483. The next prime is 21499561. The reversal of 21499501 is 10599412.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15594601 + 5904900 = 3949^2 + 2430^2 .

It is a cyclic number.

It is not a de Polignac number, because 21499501 - 2⁹ = 21498989 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21499561) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10749750 + 10749751.

It is an arithmetic number, because the mean of its divisors is an integer number (10749751).

Almost surely, 2^21499501 is an apocalyptic number.

It is an amenable number.

21499501 is a deficient number, since it is larger than the sum of its proper divisors (1).

21499501 is an equidigital number, since it uses as much as digits as its factorization.

21499501 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3240, while the sum is 31.

The square root of 21499501 is about 4636.7554388818. The cubic root of 21499501 is about 278.0627370787.

The spelling of 21499501 in words is "twenty-one million, four hundred ninety-nine thousand, five hundred one".