21012901 has 32 divisors (see below), whose sum is σ = 28062720. Its totient is φ = 15314688.

The previous prime is 21012889. The next prime is 21012913. The reversal of 21012901 is 10921012.

It is an interprime number because it is at equal distance from previous prime (21012889) and next prime (21012913).

It is not a de Polignac number, because 21012901 - 2⁷ = 21012773 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21012991) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 447060 + ... + 447106.

It is an arithmetic number, because the mean of its divisors is an integer number (876960).

Almost surely, 2^21012901 is an apocalyptic number.

It is an amenable number.

21012901 is a deficient number, since it is larger than the sum of its proper divisors (7049819).

21012901 is an equidigital number, since it uses as much as digits as its factorization.

21012901 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 118 (or 84 counting only the distinct ones).

The product of its (nonzero) digits is 36, while the sum is 16.

The square root of 21012901 is about 4583.9830933371. The cubic root of 21012901 is about 275.9489027090.

Adding to 21012901 its reverse (10921012), we get a palindrome (31933913).

The spelling of 21012901 in words is "twenty-one million, twelve thousand, nine hundred one".