21521682 has 72 divisors (see below), whose sum is σ = 58447116. Its totient is φ = 5673024.

The previous prime is 21521671. The next prime is 21521693. The reversal of 21521682 is 28612512.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21521671) and next prime (21521693).

It can be written as a sum of positive squares in 2 ways, for example, as 21150801 + 370881 = 4599^2 + 609^2 .

It is a super-2 number, since 2×21521682² = 926365592218248, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 10528 + ... + 12404.

Almost surely, 2^21521682 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21521682, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29223558).

21521682 is an abundant number, since it is smaller than the sum of its proper divisors (36925434).

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

21521682 is a wasteful number, since it uses less digits than its factorization.

21521682 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1912 (or 1902 counting only the distinct ones).

The product of its digits is 1920, while the sum is 27.

The square root of 21521682 is about 4639.1466887780. The cubic root of 21521682 is about 278.1583298356.

The spelling of 21521682 in words is "twenty-one million, five hundred twenty-one thousand, six hundred eighty-two".