21012377 has 4 divisors (see below), whose sum is σ = 21524916. Its totient is φ = 20499840.

The previous prime is 21012373. The next prime is 21012401. The reversal of 21012377 is 77321012.

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 1792921 + 19219456 = 1339^2 + 4384^2 .

It is a cyclic number.

It is not a de Polignac number, because 21012377 - 2² = 21012373 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21012371) 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, 256208 + ... + 256289.

It is an arithmetic number, because the mean of its divisors is an integer number (5381229).

Almost surely, 2^21012377 is an apocalyptic number.

It is an amenable number.

21012377 is a deficient number, since it is larger than the sum of its proper divisors (512539).

21012377 is an equidigital number, since it uses as much as digits as its factorization.

21012377 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 512538.

The product of its (nonzero) digits is 588, while the sum is 23.

The square root of 21012377 is about 4583.9259374471. The cubic root of 21012377 is about 275.9466089050.

Adding to 21012377 its reverse (77321012), we get a palindrome (98333389).

The spelling of 21012377 in words is "twenty-one million, twelve thousand, three hundred seventy-seven".