21115377 has 32 divisors (see below), whose sum is σ = 33436800. Its totient is φ = 13123584.

The previous prime is 21115373. The next prime is 21115379. The reversal of 21115377 is 77351112.

It is a happy number.

It is not a de Polignac number, because 21115377 - 2² = 21115373 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a self number, because there is not a number n which added to its sum of digits gives 21115377.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21115373) 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 31 ways as a sum of consecutive naturals, for example, 82033 + ... + 82289.

It is an arithmetic number, because the mean of its divisors is an integer number (1044900).

Almost surely, 2^21115377 is an apocalyptic number.

21115377 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

It is an amenable number.

21115377 is a deficient number, since it is larger than the sum of its proper divisors (12321423).

21115377 is a wasteful number, since it uses less digits than its factorization.

21115377 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 462 (or 456 counting only the distinct ones).

The product of its digits is 1470, while the sum is 27.

The square root of 21115377 is about 4595.1471140759. The cubic root of 21115377 is about 276.3967592397.

Adding to 21115377 its reverse (77351112), we get a palindrome (98466489).

The spelling of 21115377 in words is "twenty-one million, one hundred fifteen thousand, three hundred seventy-seven".