21405450125 has 16 divisors (see below), whose sum is σ = 28285416432. Its totient is φ = 16117043200.

The previous prime is 21405450119. The next prime is 21405450127. The reversal of 21405450125 is 52105450412.

It can be written as a sum of positive squares in 8 ways, for example, as 363626761 + 21041823364 = 19069^2 + 145058^2 .

It is not a de Polignac number, because 21405450125 - 2¹⁴ = 21405433741 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21405450127) 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, 5034452 + ... + 5038701.

It is an arithmetic number, because the mean of its divisors is an integer number (1767838527).

Almost surely, 2^21405450125 is an apocalyptic number.

21405450125 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21405450125 is a deficient number, since it is larger than the sum of its proper divisors (6879966307).

21405450125 is a wasteful number, since it uses less digits than its factorization.

21405450125 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10073185 (or 10073175 counting only the distinct ones).

The product of its (nonzero) digits is 8000, while the sum is 29.

The spelling of 21405450125 in words is "twenty-one billion, four hundred five million, four hundred fifty thousand, one hundred twenty-five".