21513401 has 12 divisors (see below), whose sum is σ = 26951652. Its totient is φ = 17021088.

The previous prime is 21513383. The next prime is 21513403. The reversal of 21513401 is 10431512.

It can be written as a sum of positive squares in 2 ways, for example, as 7645225 + 13868176 = 2765^2 + 3724^2 .

It is not a de Polignac number, because 21513401 - 2¹⁸ = 21251257 is a prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21513401.

It is not an unprimeable number, because it can be changed into a prime (21513403) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 16250 + ... + 17523.

It is an arithmetic number, because the mean of its divisors is an integer number (2245971).

Almost surely, 2^21513401 is an apocalyptic number.

It is an amenable number.

21513401 is a deficient number, since it is larger than the sum of its proper divisors (5438251).

21513401 is a wasteful number, since it uses less digits than its factorization.

21513401 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33800 (or 33793 counting only the distinct ones).

The product of its (nonzero) digits is 120, while the sum is 17.

The square root of 21513401 is about 4638.2540896333. The cubic root of 21513401 is about 278.1226491574.

Adding to 21513401 its reverse (10431512), we get a palindrome (31944913).

The spelling of 21513401 in words is "twenty-one million, five hundred thirteen thousand, four hundred one".