21345756 has 12 divisors (see below), whose sum is σ = 49806792. Its totient is φ = 7115248.

The previous prime is 21345733. The next prime is 21345757. The reversal of 21345756 is 65754312.

It is a tau number, because it is divible by the number of its divisors (12).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21345757) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 889395 + ... + 889418.

It is an arithmetic number, because the mean of its divisors is an integer number (4150566).

Almost surely, 2^21345756 is an apocalyptic number.

It is an amenable number.

21345756 is an abundant number, since it is smaller than the sum of its proper divisors (28461036).

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

21345756 is a wasteful number, since it uses less digits than its factorization.

21345756 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1778820 (or 1778818 counting only the distinct ones).

The product of its digits is 25200, while the sum is 33.

The square root of 21345756 is about 4620.1467509160. The cubic root of 21345756 is about 277.3983330192.

The spelling of 21345756 in words is "twenty-one million, three hundred forty-five thousand, seven hundred fifty-six".