21391502 has 16 divisors (see below), whose sum is σ = 36212400. Its totient is φ = 9387840.

The previous prime is 21391481. The next prime is 21391523. The reversal of 21391502 is 20519312.

It is an interprime number because it is at equal distance from previous prime (21391481) and next prime (21391523).

It is a plaindrome in base 16.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 16127 + ... + 17402.

It is an arithmetic number, because the mean of its divisors is an integer number (2263275).

Almost surely, 2^21391502 is an apocalyptic number.

21391502 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

21391502 is a deficient number, since it is larger than the sum of its proper divisors (14820898).

21391502 is a wasteful number, since it uses less digits than its factorization.

21391502 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33571.

The product of its (nonzero) digits is 540, while the sum is 23.

The square root of 21391502 is about 4625.0948098390. The cubic root of 21391502 is about 277.5963553602.

The spelling of 21391502 in words is "twenty-one million, three hundred ninety-one thousand, five hundred two".