21521402 has 16 divisors (see below), whose sum is σ = 37340352. Its totient is φ = 9111840.

The previous prime is 21521389. The next prime is 21521413. The reversal of 21521402 is 20412512.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8099 + ... + 10422.

It is an arithmetic number, because the mean of its divisors is an integer number (2333772).

Almost surely, 2^21521402 is an apocalyptic number.

21521402 is a deficient number, since it is larger than the sum of its proper divisors (15818950).

21521402 is a wasteful number, since it uses less digits than its factorization.

21521402 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18613.

The product of its (nonzero) digits is 160, while the sum is 17.

The square root of 21521402 is about 4639.1165107162. The cubic root of 21521402 is about 278.1571235378.

Adding to 21521402 its reverse (20412512), we get a palindrome (41933914).

The spelling of 21521402 in words is "twenty-one million, five hundred twenty-one thousand, four hundred two".