21400257515 has 16 divisors (see below), whose sum is σ = 31606534848. Its totient is φ = 13545657216.

The previous prime is 21400257491. The next prime is 21400257521. The reversal of 21400257515 is 51575200412.

It is not a de Polignac number, because 21400257515 - 2¹⁴ = 21400241131 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 23516312 + ... + 23517221.

It is an arithmetic number, because the mean of its divisors is an integer number (1975408428).

Almost surely, 2^21400257515 is an apocalyptic number.

21400257515 is a deficient number, since it is larger than the sum of its proper divisors (10206277333).

21400257515 is a wasteful number, since it uses less digits than its factorization.

21400257515 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 47033558.

The product of its (nonzero) digits is 14000, while the sum is 32.

Adding to 21400257515 its reverse (51575200412), we get a palindrome (72975457927).

The spelling of 21400257515 in words is "twenty-one billion, four hundred million, two hundred fifty-seven thousand, five hundred fifteen".