21402890 has 16 divisors (see below), whose sum is σ = 38586240. Its totient is φ = 8547600.

The previous prime is 21402877. The next prime is 21402893. The reversal of 21402890 is 9820412.

It is not an unprimeable number, because it can be changed into a prime (21402893) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7115 + ... + 9665.

It is an arithmetic number, because the mean of its divisors is an integer number (2411640).

Almost surely, 2^21402890 is an apocalyptic number.

21402890 is a deficient number, since it is larger than the sum of its proper divisors (17183350).

21402890 is a wasteful number, since it uses less digits than its factorization.

21402890 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3397.

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

The square root of 21402890 is about 4626.3257559320. The cubic root of 21402890 is about 277.6456071064.

The spelling of 21402890 in words is "twenty-one million, four hundred two thousand, eight hundred ninety".