21022557 has 16 divisors (see below), whose sum is σ = 30638592. Its totient is φ = 12764160.

The previous prime is 21022553. The next prime is 21022597. The reversal of 21022557 is 75522012.

It is not a de Polignac number, because 21022557 - 2² = 21022553 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21022553) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5068 + ... + 8229.

It is an arithmetic number, because the mean of its divisors is an integer number (1914912).

Almost surely, 2^21022557 is an apocalyptic number.

It is an amenable number.

21022557 is a deficient number, since it is larger than the sum of its proper divisors (9616035).

21022557 is a wasteful number, since it uses less digits than its factorization.

21022557 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13348.

The product of its (nonzero) digits is 1400, while the sum is 24.

The square root of 21022557 is about 4585.0362048734. The cubic root of 21022557 is about 275.9911649136.

Adding to 21022557 its reverse (75522012), we get a palindrome (96544569).

The spelling of 21022557 in words is "twenty-one million, twenty-two thousand, five hundred fifty-seven".