21091430 has 16 divisors (see below), whose sum is σ = 38060064. Its totient is φ = 8415360.

The previous prime is 21091409. The next prime is 21091451. The reversal of 21091430 is 3419012.

It is an interprime number because it is at equal distance from previous prime (21091409) and next prime (21091451).

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, 1895 + ... + 6765.

It is an arithmetic number, because the mean of its divisors is an integer number (2378754).

Almost surely, 2^21091430 is an apocalyptic number.

21091430 is a deficient number, since it is larger than the sum of its proper divisors (16968634).

21091430 is a wasteful number, since it uses less digits than its factorization.

21091430 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5311.

The product of its (nonzero) digits is 216, while the sum is 20.

The square root of 21091430 is about 4592.5406911643. The cubic root of 21091430 is about 276.2922323045.

The spelling of 21091430 in words is "twenty-one million, ninety-one thousand, four hundred thirty".