21357455 has 32 divisors (see below), whose sum is σ = 31325184. Its totient is φ = 13660416.

The previous prime is 21357451. The next prime is 21357461. The reversal of 21357455 is 55475312.

It is not a de Polignac number, because 21357455 - 2² = 21357451 is a prime.

It is a super-2 number, since 2×21357455² = 912281768154050, 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 (21357451) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 34307 + ... + 34923.

It is an arithmetic number, because the mean of its divisors is an integer number (978912).

Almost surely, 2^21357455 is an apocalyptic number.

21357455 is a deficient number, since it is larger than the sum of its proper divisors (9967729).

21357455 is a wasteful number, since it uses less digits than its factorization.

21357455 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 695.

The product of its digits is 21000, while the sum is 32.

The square root of 21357455 is about 4621.4126628121. The cubic root of 21357455 is about 277.4490018016.

It can be divided in two parts, 21357 and 455, that added together give a palindrome (21812).

The spelling of 21357455 in words is "twenty-one million, three hundred fifty-seven thousand, four hundred fifty-five".