21261373 has 16 divisors (see below), whose sum is σ = 25850880. Its totient is φ = 17070336.

The previous prime is 21261337. The next prime is 21261377. The reversal of 21261373 is 37316212.

It is a cyclic number.

It is not a de Polignac number, because 21261373 - 2¹³ = 21253181 is a prime.

It is a super-3 number, since 3×21261373³ (a number of 23 digits) contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21261377) 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, 44148 + ... + 44626.

It is an arithmetic number, because the mean of its divisors is an integer number (1615680).

Almost surely, 2^21261373 is an apocalyptic number.

It is an amenable number.

21261373 is a deficient number, since it is larger than the sum of its proper divisors (4589507).

21261373 is a wasteful number, since it uses less digits than its factorization.

21261373 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 876.

The product of its digits is 1512, while the sum is 25.

The square root of 21261373 is about 4611.0056386866. The cubic root of 21261373 is about 277.0323177766.

Adding to 21261373 its reverse (37316212), we get a palindrome (58577585).

The spelling of 21261373 in words is "twenty-one million, two hundred sixty-one thousand, three hundred seventy-three".