21562157 has 4 divisors (see below), whose sum is σ = 22144956. Its totient is φ = 20979360.

The previous prime is 21562133. The next prime is 21562217. The reversal of 21562157 is 75126512.

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 17355556 + 4206601 = 4166^2 + 2051^2 .

It is a cyclic number.

It is not a de Polignac number, because 21562157 - 2¹⁴ = 21545773 is a prime.

It is a super-2 number, since 2×21562157² = 929853228985298, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21562117) 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, 291344 + ... + 291417.

It is an arithmetic number, because the mean of its divisors is an integer number (5536239).

Almost surely, 2^21562157 is an apocalyptic number.

It is an amenable number.

21562157 is a deficient number, since it is larger than the sum of its proper divisors (582799).

21562157 is an equidigital number, since it uses as much as digits as its factorization.

21562157 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 582798.

The product of its digits is 4200, while the sum is 29.

The square root of 21562157 is about 4643.5069721063. The cubic root of 21562157 is about 278.3325945295.

Adding to 21562157 its reverse (75126512), we get a palindrome (96688669).

The spelling of 21562157 in words is "twenty-one million, five hundred sixty-two thousand, one hundred fifty-seven".