21356916 has 24 divisors (see below), whose sum is σ = 56952000. Its totient is φ = 6101952.

The previous prime is 21356899. The next prime is 21356917. The reversal of 21356916 is 61965312.

It is a happy number.

It is a super-2 number, since 2×21356916² = 912235722062112, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21356917) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 127041 + ... + 127208.

It is an arithmetic number, because the mean of its divisors is an integer number (2373000).

Almost surely, 2^21356916 is an apocalyptic number.

It is an amenable number.

21356916 is an abundant number, since it is smaller than the sum of its proper divisors (35595084).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21356916 is a wasteful number, since it uses less digits than its factorization.

21356916 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 254263 (or 254261 counting only the distinct ones).

The product of its digits is 9720, while the sum is 33.

The square root of 21356916 is about 4621.3543469420. The cubic root of 21356916 is about 277.4466677802.

The spelling of 21356916 in words is "twenty-one million, three hundred fifty-six thousand, nine hundred sixteen".