21351930 has 16 divisors (see below), whose sum is σ = 51244704. Its totient is φ = 5693840.

The previous prime is 21351919. The next prime is 21351943. The reversal of 21351930 is 3915312.

It is a happy number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21351930.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 355836 + ... + 355895.

It is an arithmetic number, because the mean of its divisors is an integer number (3202794).

Almost surely, 2^21351930 is an apocalyptic number.

21351930 is an abundant number, since it is smaller than the sum of its proper divisors (29892774).

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

21351930 is a wasteful number, since it uses less digits than its factorization.

21351930 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 711741.

The product of its (nonzero) digits is 810, while the sum is 24.

The square root of 21351930 is about 4620.8148632032. The cubic root of 21351930 is about 277.4250751378.

The spelling of 21351930 in words is "twenty-one million, three hundred fifty-one thousand, nine hundred thirty".