21077551 has 16 divisors (see below), whose sum is σ = 23989248. Its totient is φ = 18345600.

The previous prime is 21077549. The next prime is 21077561. The reversal of 21077551 is 15577012.

It is a cyclic number.

It is not a de Polignac number, because 21077551 - 2¹ = 21077549 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21077561) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 38260 + ... + 38806.

It is an arithmetic number, because the mean of its divisors is an integer number (1499328).

Almost surely, 2^21077551 is an apocalyptic number.

21077551 is a deficient number, since it is larger than the sum of its proper divisors (2911697).

21077551 is a wasteful number, since it uses less digits than its factorization.

21077551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 702.

The product of its (nonzero) digits is 2450, while the sum is 28.

The square root of 21077551 is about 4591.0294052641. The cubic root of 21077551 is about 276.2316152463.

The spelling of 21077551 in words is "twenty-one million, seventy-seven thousand, five hundred fifty-one".