1221372157 has 8 divisors (see below), whose sum is σ = 1315137600. Its totient is φ = 1130042304.

The previous prime is 1221372143. The next prime is 1221372161. The reversal of 1221372157 is 7512731221.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1221372157 - 2⁷ = 1221372029 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 (1221373157) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 607857 + ... + 609862.

It is an arithmetic number, because the mean of its divisors is an integer number (164392200).

Almost surely, 2^1221372157 is an apocalyptic number.

1221372157 is a gapful number since it is divisible by the number (17) formed by its first and last digit.

It is an amenable number.

1221372157 is a deficient number, since it is larger than the sum of its proper divisors (93765443).

1221372157 is a wasteful number, since it uses less digits than its factorization.

1221372157 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1217795.

The product of its digits is 5880, while the sum is 31.

The square root of 1221372157 is about 34948.1352435291. The cubic root of 1221372157 is about 1068.9301785664.

The spelling of 1221372157 in words is "one billion, two hundred twenty-one million, three hundred seventy-two thousand, one hundred fifty-seven".