21906077 has 4 divisors (see below), whose sum is σ = 21926940. Its totient is φ = 21885216.

The previous prime is 21906061. The next prime is 21906083. The reversal of 21906077 is 77060912.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 2493241 + 19412836 = 1579^2 + 4406^2 .

It is a cyclic number.

It is not a de Polignac number, because 21906077 - 2⁴ = 21906061 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 (21906007) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8768 + ... + 10985.

It is an arithmetic number, because the mean of its divisors is an integer number (5481735).

Almost surely, 2^21906077 is an apocalyptic number.

It is an amenable number.

21906077 is a deficient number, since it is larger than the sum of its proper divisors (20863).

21906077 is a wasteful number, since it uses less digits than its factorization.

21906077 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20862.

The product of its (nonzero) digits is 5292, while the sum is 32.

The square root of 21906077 is about 4680.3928253940. The cubic root of 21906077 is about 279.8046128380.

Adding to 21906077 its reverse (77060912), we get a palindrome (98966989).

The spelling of 21906077 in words is "twenty-one million, nine hundred six thousand, seventy-seven".