21221523163425 has 24 divisors (see below), whose sum is σ = 37785194065024. Its totient is φ = 10447519095360.

The previous prime is 21221523163397. The next prime is 21221523163469. The reversal of 21221523163425 is 52436132512212.

It is not a de Polignac number, because 21221523163425 - 2⁹ = 21221523162913 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 10882831417 + ... + 10882833366.

Almost surely, 2^{21221523163425} is an apocalyptic number.

21221523163425 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21221523163425 is a deficient number, since it is larger than the sum of its proper divisors (16563670901599).

21221523163425 is a wasteful number, since it uses less digits than its factorization.

21221523163425 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21765664809 (or 21765664804 counting only the distinct ones).

The product of its digits is 172800, while the sum is 39.

Adding to 21221523163425 its reverse (52436132512212), we get a palindrome (73657655675637).

The spelling of 21221523163425 in words is "twenty-one trillion, two hundred twenty-one billion, five hundred twenty-three million, one hundred sixty-three thousand, four hundred twenty-five".