21213902 has 16 divisors (see below), whose sum is σ = 32341680. Its totient is φ = 10435008.

The previous prime is 21213901. The next prime is 21213911. The reversal of 21213902 is 20931212.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21213901) by changing a digit.

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, 37808 + ... + 38364.

It is an arithmetic number, because the mean of its divisors is an integer number (2021355).

Almost surely, 2^21213902 is an apocalyptic number.

21213902 is a deficient number, since it is larger than the sum of its proper divisors (11127778).

21213902 is a wasteful number, since it uses less digits than its factorization.

21213902 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 835.

The product of its (nonzero) digits is 216, while the sum is 20.

The square root of 21213902 is about 4605.8551866076. The cubic root of 21213902 is about 276.8259842709.

The spelling of 21213902 in words is "twenty-one million, two hundred thirteen thousand, nine hundred two".