21212477 has 8 divisors (see below), whose sum is σ = 24921120. Its totient is φ = 17800560.

The previous prime is 21212467. The next prime is 21212483. The reversal of 21212477 is 77421212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21212477 - 2⁴ = 21212461 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 (21212467) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 74027 + ... + 74312.

It is an arithmetic number, because the mean of its divisors is an integer number (3115140).

Almost surely, 2^21212477 is an apocalyptic number.

It is an amenable number.

21212477 is a deficient number, since it is larger than the sum of its proper divisors (3708643).

21212477 is a wasteful number, since it uses less digits than its factorization.

21212477 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 148363.

The product of its digits is 1568, while the sum is 26.

The square root of 21212477 is about 4605.7004896107. The cubic root of 21212477 is about 276.8197857277.

Adding to 21212477 its reverse (77421212), we get a palindrome (98633689).

The spelling of 21212477 in words is "twenty-one million, two hundred twelve thousand, four hundred seventy-seven".