21077481 has 4 divisors (see below), whose sum is σ = 28103312. Its totient is φ = 14051652.

The previous prime is 21077477. The next prime is 21077527. The reversal of 21077481 is 18477012.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 21077481 - 2² = 21077477 is a prime.

It is a super-2 number, since 2×21077481² = 888520410610722, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21077401) 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 3 ways as a sum of consecutive naturals, for example, 3512911 + ... + 3512916.

It is an arithmetic number, because the mean of its divisors is an integer number (7025828).

Almost surely, 2^21077481 is an apocalyptic number.

It is an amenable number.

21077481 is a deficient number, since it is larger than the sum of its proper divisors (7025831).

21077481 is an equidigital number, since it uses as much as digits as its factorization.

21077481 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7025830.

The product of its (nonzero) digits is 3136, while the sum is 30.

The square root of 21077481 is about 4591.0217816952. The cubic root of 21077481 is about 276.2313094512.

The spelling of 21077481 in words is "twenty-one million, seventy-seven thousand, four hundred eighty-one".