21356613 has 24 divisors (see below), whose sum is σ = 32637696. Its totient is φ = 13435200.

The previous prime is 21356611. The next prime is 21356633. The reversal of 21356613 is 31665312.

It is not a de Polignac number, because 21356613 - 2¹ = 21356611 is a prime.

It is a super-2 number, since 2×21356613² = 912209837663538, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21356611) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 10506 + ... + 12372.

It is an arithmetic number, because the mean of its divisors is an integer number (1359904).

Almost surely, 2^21356613 is an apocalyptic number.

It is an amenable number.

21356613 is a deficient number, since it is larger than the sum of its proper divisors (11281083).

21356613 is a wasteful number, since it uses less digits than its factorization.

21356613 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1945 (or 1942 counting only the distinct ones).

The product of its digits is 3240, while the sum is 27.

The square root of 21356613 is about 4621.3215642281. The cubic root of 21356613 is about 277.4453556879.

The spelling of 21356613 in words is "twenty-one million, three hundred fifty-six thousand, six hundred thirteen".