21089402 has 4 divisors (see below), whose sum is σ = 31634106. Its totient is φ = 10544700.

The previous prime is 21089381. The next prime is 21089407. The reversal of 21089402 is 20498012.

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

It can be written as a sum of positive squares in only one way, i.e., 16556761 + 4532641 = 4069^2 + 2129^2 .

It is not an unprimeable number, because it can be changed into a prime (21089407) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5272349 + ... + 5272352.

Almost surely, 2^21089402 is an apocalyptic number.

21089402 is a deficient number, since it is larger than the sum of its proper divisors (10544704).

21089402 is a wasteful number, since it uses less digits than its factorization.

21089402 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10544703.

The product of its (nonzero) digits is 1152, while the sum is 26.

The square root of 21089402 is about 4592.3198930388. The cubic root of 21089402 is about 276.2833765969.

The spelling of 21089402 in words is "twenty-one million, eighty-nine thousand, four hundred two".