21756930 has 32 divisors (see below), whose sum is σ = 56234304. Its totient is φ = 5355456.

The previous prime is 21756901. The next prime is 21756949. The reversal of 21756930 is 3965712.

It is a junction number, because it is equal to n+sod(n) for n = 21756891 and 21756900.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 27504 + ... + 28283.

It is an arithmetic number, because the mean of its divisors is an integer number (1757322).

Almost surely, 2^21756930 is an apocalyptic number.

21756930 is an abundant number, since it is smaller than the sum of its proper divisors (34477374).

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

21756930 is a wasteful number, since it uses less digits than its factorization.

21756930 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 55810.

The product of its (nonzero) digits is 11340, while the sum is 33.

The square root of 21756930 is about 4664.4324413588. The cubic root of 21756930 is about 279.1681518695.

The spelling of 21756930 in words is "twenty-one million, seven hundred fifty-six thousand, nine hundred thirty".