21290634 has 16 divisors (see below), whose sum is σ = 47312640. Its totient is φ = 7096860.

The previous prime is 21290629. The next prime is 21290641. The reversal of 21290634 is 43609212.

21290634 is a `hidden beast` number, since 2 + 1 + 29 + 0 + 634 = 666.

It is a super-2 number, since 2×21290634² = 906582192243912, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a junction number, because it is equal to n+sod(n) for n = 21290598 and 21290607.

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, 197082 + ... + 197189.

It is an arithmetic number, because the mean of its divisors is an integer number (2957040).

Almost surely, 2^21290634 is an apocalyptic number.

21290634 is an abundant number, since it is smaller than the sum of its proper divisors (26022006).

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

21290634 is a wasteful number, since it uses less digits than its factorization.

21290634 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 394282 (or 394276 counting only the distinct ones).

The product of its (nonzero) digits is 2592, while the sum is 27.

The square root of 21290634 is about 4614.1774998368. The cubic root of 21290634 is about 277.1593482487.

Adding to 21290634 its reverse (43609212), we get a palindrome (64899846).

The spelling of 21290634 in words is "twenty-one million, two hundred ninety thousand, six hundred thirty-four".