21697970139593 has 4 divisors (see below), whose sum is σ = 23670512879568. Its totient is φ = 19725427399620.

The previous prime is 21697970139551. The next prime is 21697970139647. The reversal of 21697970139593 is 39593107979612.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21697970139593 - 2¹⁴ = 21697970123209 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21697970139193) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 986271369971 + ... + 986271369992.

It is an arithmetic number, because the mean of its divisors is an integer number (5917628219892).

Almost surely, 2^{21697970139593} is an apocalyptic number.

It is an amenable number.

21697970139593 is a deficient number, since it is larger than the sum of its proper divisors (1972542739975).

21697970139593 is a wasteful number, since it uses less digits than its factorization.

21697970139593 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1972542739974.

The product of its (nonzero) digits is 173604060, while the sum is 71.

Adding to 21697970139593 its sum of digits (71), we get a square (21697970139664 = 4658108²).

The spelling of 21697970139593 in words is "twenty-one trillion, six hundred ninety-seven billion, nine hundred seventy million, one hundred thirty-nine thousand, five hundred ninety-three".