21521630 has 16 divisors (see below), whose sum is σ = 41719104. Its totient is φ = 7946400.

The previous prime is 21521627. The next prime is 21521653. The reversal of 21521630 is 3612512.

It is a congruent number.

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, 82646 + ... + 82905.

It is an arithmetic number, because the mean of its divisors is an integer number (2607444).

Almost surely, 2^21521630 is an apocalyptic number.

21521630 is a deficient number, since it is larger than the sum of its proper divisors (20197474).

21521630 is a wasteful number, since it uses less digits than its factorization.

21521630 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 165571.

The product of its (nonzero) digits is 360, while the sum is 20.

The square root of 21521630 is about 4639.1410842957. The cubic root of 21521630 is about 278.1581058096.

The spelling of 21521630 in words is "twenty-one million, five hundred twenty-one thousand, six hundred thirty".