21521629 has 16 divisors (see below), whose sum is σ = 23519232. Its totient is φ = 19636848.

The previous prime is 21521627. The next prime is 21521653. The reversal of 21521629 is 92612512.

It is not a de Polignac number, because 21521629 - 2¹ = 21521627 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 9.

It is a junction number, because it is equal to n+sod(n) for n = 21521597 and 21521606.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21521627) 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, 46252 + ... + 46714.

It is an arithmetic number, because the mean of its divisors is an integer number (1469952).

Almost surely, 2^21521629 is an apocalyptic number.

It is an amenable number.

21521629 is a deficient number, since it is larger than the sum of its proper divisors (1997603).

21521629 is a wasteful number, since it uses less digits than its factorization.

21521629 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 576.

The product of its digits is 2160, while the sum is 28.

The square root of 21521629 is about 4639.1409765171. The cubic root of 21521629 is about 278.1581015014.

The spelling of 21521629 in words is "twenty-one million, five hundred twenty-one thousand, six hundred twenty-nine".