21063381 has 16 divisors (see below), whose sum is σ = 30287040. Its totient is φ = 12977280.

The previous prime is 21063373. The next prime is 21063403. The reversal of 21063381 is 18336012.

It is not a de Polignac number, because 21063381 - 2³ = 21063373 is a prime.

It is a super-2 number, since 2×21063381² = 887332038302322, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21063311) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2170 + ... + 6843.

It is an arithmetic number, because the mean of its divisors is an integer number (1892940).

Almost surely, 2^21063381 is an apocalyptic number.

It is an amenable number.

21063381 is a deficient number, since it is larger than the sum of its proper divisors (9223659).

21063381 is a wasteful number, since it uses less digits than its factorization.

21063381 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9076.

The product of its (nonzero) digits is 864, while the sum is 24.

The square root of 21063381 is about 4589.4859189238. The cubic root of 21063381 is about 276.1696997758.

Adding to 21063381 its reverse (18336012), we get a palindrome (39399393).

The spelling of 21063381 in words is "twenty-one million, sixty-three thousand, three hundred eighty-one".