21377573 has 12 divisors (see below), whose sum is σ = 24969420. Its totient is φ = 18248832.

The previous prime is 21377567. The next prime is 21377581. The reversal of 21377573 is 37577312.

It can be written as a sum of positive squares in 2 ways, for example, as 13300609 + 8076964 = 3647^2 + 2842^2 .

It is not a de Polignac number, because 21377573 - 2⁶ = 21377509 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21377513) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 13613 + ... + 15101.

It is an arithmetic number, because the mean of its divisors is an integer number (2080785).

Almost surely, 2^21377573 is an apocalyptic number.

It is an amenable number.

21377573 is a deficient number, since it is larger than the sum of its proper divisors (3591847).

21377573 is a wasteful number, since it uses less digits than its factorization.

21377573 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1796 (or 1789 counting only the distinct ones).

The product of its digits is 30870, while the sum is 35.

The square root of 21377573 is about 4623.5887576643. The cubic root of 21377573 is about 277.5360903200.

The spelling of 21377573 in words is "twenty-one million, three hundred seventy-seven thousand, five hundred seventy-three".