21069951 has 12 divisors (see below), whose sum is σ = 32680152. Its totient is φ = 12039888.

The previous prime is 21069947. The next prime is 21069967. The reversal of 21069951 is 15996012.

It is not a de Polignac number, because 21069951 - 2² = 21069947 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21069901) by changing a digit.

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 11 ways as a sum of consecutive naturals, for example, 71520 + ... + 71813.

It is an arithmetic number, because the mean of its divisors is an integer number (2723346).

Almost surely, 2^21069951 is an apocalyptic number.

21069951 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21069951 is a deficient number, since it is larger than the sum of its proper divisors (11610201).

21069951 is a wasteful number, since it uses less digits than its factorization.

21069951 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 143350 (or 143343 counting only the distinct ones).

The product of its (nonzero) digits is 4860, while the sum is 33.

The square root of 21069951 is about 4590.2016295583. The cubic root of 21069951 is about 276.1984106826.

The spelling of 21069951 in words is "twenty-one million, sixty-nine thousand, nine hundred fifty-one".