21528635397 has 16 divisors (see below), whose sum is σ = 28919217600. Its totient is φ = 14245545600.

The previous prime is 21528635393. The next prime is 21528635437. The reversal of 21528635397 is 79353682512.

It is not a de Polignac number, because 21528635397 - 2² = 21528635393 is a prime.

It is a super-2 number, since 2×21528635397² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21528635393) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 244854 + ... + 320952.

It is an arithmetic number, because the mean of its divisors is an integer number (1807451100).

Almost surely, 2^21528635397 is an apocalyptic number.

It is an amenable number.

21528635397 is a deficient number, since it is larger than the sum of its proper divisors (7390582203).

21528635397 is a wasteful number, since it uses less digits than its factorization.

21528635397 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 76804.

The product of its digits is 2721600, while the sum is 51.

The spelling of 21528635397 in words is "twenty-one billion, five hundred twenty-eight million, six hundred thirty-five thousand, three hundred ninety-seven".