21129902 has 4 divisors (see below), whose sum is σ = 31694856. Its totient is φ = 10564950.

The previous prime is 21129887. The next prime is 21129937. The reversal of 21129902 is 20992112.

It is a happy number.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5282474 + ... + 5282477.

It is an arithmetic number, because the mean of its divisors is an integer number (7923714).

Almost surely, 2^21129902 is an apocalyptic number.

21129902 is a deficient number, since it is larger than the sum of its proper divisors (10564954).

21129902 is a wasteful number, since it uses less digits than its factorization.

21129902 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10564953.

The product of its (nonzero) digits is 648, while the sum is 26.

The square root of 21129902 is about 4596.7273140790. The cubic root of 21129902 is about 276.4601213215.

The spelling of 21129902 in words is "twenty-one million, one hundred twenty-nine thousand, nine hundred two".