21351013 has 2 divisors, whose sum is σ = 21351014. Its totient is φ = 21351012.

The previous prime is 21351007. The next prime is 21351017. The reversal of 21351013 is 31015312.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14884164 + 6466849 = 3858^2 + 2543^2 .

It is a cyclic number.

It is not a de Polignac number, because 21351013 - 2⁹ = 21350501 is a prime.

It is a super-2 number, since 2×21351013² = 911731512252338, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21351017) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10675506 + 10675507.

It is an arithmetic number, because the mean of its divisors is an integer number (10675507).

Almost surely, 2^21351013 is an apocalyptic number.

It is an amenable number.

21351013 is a deficient number, since it is larger than the sum of its proper divisors (1).

21351013 is an equidigital number, since it uses as much as digits as its factorization.

21351013 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 90, while the sum is 16.

The square root of 21351013 is about 4620.7156372147. The cubic root of 21351013 is about 277.4211035618.

Adding to 21351013 its reverse (31015312), we get a palindrome (52366325).

The spelling of 21351013 in words is "twenty-one million, three hundred fifty-one thousand, thirteen".