21521802 has 32 divisors (see below), whose sum is σ = 44634240. Its totient is φ = 6913280.

The previous prime is 21521771. The next prime is 21521803. The reversal of 21521802 is 20812512.

It is a happy number.

It is a super-2 number, since 2×21521802² = 926375922654408, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21521803) 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, 21403 + ... + 22385.

It is an arithmetic number, because the mean of its divisors is an integer number (1394820).

Almost surely, 2^21521802 is an apocalyptic number.

21521802 is an abundant number, since it is smaller than the sum of its proper divisors (23112438).

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

21521802 is a wasteful number, since it uses less digits than its factorization.

21521802 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1118.

The product of its (nonzero) digits is 320, while the sum is 21.

The square root of 21521802 is about 4639.1596221730. The cubic root of 21521802 is about 278.1588468171.

The spelling of 21521802 in words is "twenty-one million, five hundred twenty-one thousand, eight hundred two".