21512053 has 2 divisors, whose sum is σ = 21512054. Its totient is φ = 21512052.

The previous prime is 21512033. The next prime is 21512063. The reversal of 21512053 is 35021512.

It is the 1894-th star number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21316689 + 195364 = 4617^2 + 442^2 .

It is a cyclic number.

It is not a de Polignac number, because 21512053 - 2¹⁷ = 21380981 is a prime.

It is a super-3 number, since 3×21512053³ (a number of 23 digits) contains 333 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21512053.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21512033) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10756026 + 10756027.

It is an arithmetic number, because the mean of its divisors is an integer number (10756027).

Almost surely, 2^21512053 is an apocalyptic number.

It is an amenable number.

21512053 is a deficient number, since it is larger than the sum of its proper divisors (1).

21512053 is an equidigital number, since it uses as much as digits as its factorization.

21512053 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 300, while the sum is 19.

The square root of 21512053 is about 4638.1087740587. The cubic root of 21512053 is about 278.1168401090.

Adding to 21512053 its reverse (35021512), we get a palindrome (56533565).

The spelling of 21512053 in words is "twenty-one million, five hundred twelve thousand, fifty-three".