1561921952429 has 4 divisors (see below), whose sum is σ = 1588395205920. Its totient is φ = 1535448698940.

The previous prime is 1561921952399. The next prime is 1561921952447. The reversal of 1561921952429 is 9242591291651.

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 a de Polignac number, because none of the positive numbers 2^k-1561921952429 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 (1561921952489) 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, 13236626657 + ... + 13236626774.

It is an arithmetic number, because the mean of its divisors is an integer number (397098801480).

Almost surely, 2^{1561921952429} is an apocalyptic number.

It is an amenable number.

1561921952429 is a deficient number, since it is larger than the sum of its proper divisors (26473253491).

1561921952429 is an equidigital number, since it uses as much as digits as its factorization.

1561921952429 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26473253490.

The product of its digits is 3499200, while the sum is 56.

The spelling of 1561921952429 in words is "one trillion, five hundred sixty-one billion, nine hundred twenty-one million, nine hundred fifty-two thousand, four hundred twenty-nine".