21315402 has 24 divisors (see below), whose sum is σ = 46968480. Its totient is φ = 6984360.

The previous prime is 21315391. The next prime is 21315421. The reversal of 21315402 is 20451312.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is an unprimeable number.

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 11 ways as a sum of consecutive naturals, for example, 8974 + ... + 11097.

It is an arithmetic number, because the mean of its divisors is an integer number (1957020).

Almost surely, 2^21315402 is an apocalyptic number.

21315402 is an abundant number, since it is smaller than the sum of its proper divisors (25653078).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21315402 is a wasteful number, since it uses less digits than its factorization.

21315402 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20138 (or 20135 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 18.

The square root of 21315402 is about 4616.8606216779. The cubic root of 21315402 is about 277.2667823829.

Adding to 21315402 its reverse (20451312), we get a palindrome (41766714).

The spelling of 21315402 in words is "twenty-one million, three hundred fifteen thousand, four hundred two".