21210902 has 4 divisors (see below), whose sum is σ = 31816356. Its totient is φ = 10605450.

The previous prime is 21210901. The next prime is 21210907. The reversal of 21210902 is 20901212.

It is a semiprime because it is the product of two primes.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21210901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5302724 + ... + 5302727.

It is an arithmetic number, because the mean of its divisors is an integer number (7954089).

Almost surely, 2^21210902 is an apocalyptic number.

21210902 is a deficient number, since it is larger than the sum of its proper divisors (10605454).

21210902 is a wasteful number, since it uses less digits than its factorization.

21210902 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10605453.

The product of its (nonzero) digits is 72, while the sum is 17.

The square root of 21210902 is about 4605.5295026739. The cubic root of 21210902 is about 276.8129343834.

The spelling of 21210902 in words is "twenty-one million, two hundred ten thousand, nine hundred two".